TOM SWIFT

Before young Tom Swift, captain of the expedition, could respond, his pal Bud Barclay exclaimed excitedly, "Already? Man, this whale of a sub is faster than a greased barracuda! Or have I said that before?"

Tom grinned at his friend’s compliment as he joined Slim at the wheel. Gazing out the cabin’s broad, curving viewpane, the blond-haired scientist-inventor exchanged his grin for a frown. In the darkness beyond the craft’s aqualamp beam lay mystery and adventure! "Not much to see so far," he murmured.

Slim gestured at one of the screens on the control board. "But the sonarscope readings match the topography readout perfectly. We’ve locked on to the same route you fellows recorded on your first visit in the Ocean Arrow."

"Let’s hope this visit is a little less rocky," Bud remarked wryly and dryly.

While combing the Atlantic seabed for a lost rocket in Tom’s original diving seacopter, Tom and Bud had discovered a sunken city of ancient, overgrown ruins that accompanying scientists believed were traces of the legendary lost island of Atlantis. Tom had led an eventful and danger-filled life since that distant day, his inventions carrying him to many corners of the globe and up into the void of space surrounding it. But he had always planned a return to the seafloor city, and during his most recent expedition—to the Yucatan jungles with his electronic retroscope camera—his father had thrown the full weight of their mammoth invention facility behind the effort. Months of strenuous preparation were at last bearing fruit, and the present preliminary survey of the site was the project’s first step.

Less than an hour had passed since Tom and his crew had ended their brief stopover in Helium City, Enterprises’ gas extraction station on the ocean floor near the Mid-Atlantic Ridge. Leaving the hydrodome and the jagged spine of subsea mountains behind them, the Deepwing was now approaching the chain of geological features known as the Horseshoe Seamounts, which lay between the Madeira Islands to the south and the coast of Portugal to the northeast. It was here, among looming plateaus and overhanging cliffs, that the seacopter had been half-buried by falling boulders. Tom and Bud had nearly ended their lives trapped in a deep chasm which had never known the sun.

Zimby Cox, an experienced company sub captain with a background in marine technology, joined the watchers at the viewpane. "How’s it hangin’ back there, Zim?" asked Bud.

"Shipshape in the cargo hold," replied Cox, whose full given name, rarely pronounced aloud, was Zimbalest. "That watery warehouse must be as big as the hangar inside your Flying Lab, Tom." The giant-sized stratoship, the Sky Queen, carried a hold on the lowest of its three decks large enough to serve as a hangar for shuttle aircraft.

"In cubic feet you’re just about right," Tom stated; "if you add the port and starboard holds together."

The Deepwing was one of the three new oversized seacopters that Tom had been designing for some time now, and the first of the three to be completed and ready for service. These craft, several times the size of the Ocean Arrow and the later Sea Hound, had a wide curving fore-edge that tapered smoothly toward the stern into a protruding tail section. The overall effect suggested the kiteshaped fins and flattened body of the manta ray—also called the devilfish. Nicknamed the mantacopters, each submersible sported two rotor wells which vertically penetrated the low flat hull on either side of the prow control cabin. The whirling prop blades were used to hold the ship underwater against the effect of its buoyancy. The mantacops had been developed to carry the bulky equipment and extensive supplies required by large undersea operations. Like the other seacopters, they were powered by compact atomic reactors and driven by jets of superheated steam.

Leaning over the controls, Tom now swiveled the diamond-bright aqualamp beam and set it to a greater range. A wall of gray rock, dotted with long streamers of deepwater vegetation, leapt into view. "Stand-to, Slim," Tom directed. Slim Davis immediately reversed the powerful steam jets. The Deepwing eased to a hovering halt, thirty feet above the floor.

"Shouldn’t Cromwell be up here to see this?" Bud asked. "I mean, he is here as an observer."

"Yep. An official observer," agreed Tom. A slight tinge in the young inventor’s voice made Bud smile. Lieutenant Cromwell, an officer in the US Navy, had joined the Enterprises expedition at the request of ONDAR, the Office of National Defense Applied Research. Tom had worked with this government agency before. In the present case the request was backed by the Navy and the State Department, who were concerned with various legal issues surrounding American activity at the site of the ruins, which lay in international waters. Tom and his father cooperated. But Bud knew his pal was always somewhat leery of any "official" involvement that might complicate a scientific project or compromise its goals.

A rough-hewn heavyset man who somehow seemed ill at ease in his Navy uniform, Darrin Cromwell had already rubbed Tom and Bud the wrong way in the several days since his arrival at Swift Enterprises. He had a habit of pestering them with aggressive questions. Tom assumed they were relevant to legal matters. But he didn’t like them. And Bud, characteristically, was willing to add that he didn’t like the man himself.

"Lieutenant Cromwell to control," Tom intercommed. "We’re beginning our approach to the site."

"Be right there," came the reply over the speaker. In a moment the Navy man entered the spacious cabin through one of the watertight bulkhead doors that connected the control deck to the string of special-purpose compartments that wound their way around the two rotor wells. "So this is it, hmm, boys? Submarine city of gold! Picked up any gold traces on your metal-detector yet?"

"Nothing unusual," Tom responded, gesturing at Slim to resume forward motion. "The inhabitants must’ve mined the gold some distance from the city. Didn’t Admiral Hopkins brief you on all the specs, Lieutenant?"

Cromwell gave a dismissive shrug. "Oh, the documentation was fairly thorough. But those details aren’t important to me. My job is simply to report your findings. Old Hopkins said most of the operation is top secret."

"Sure," Bud retorted. "Imagine what’d happen if word leaked out about all that gold lying around unclaimed!"

The officer hissed out a chuckle. "A submarine gold rush probably."

"Worse than that," Tom said gravely. "It could lead to real international trouble."

"Right, right. I see what you mean." Cromwell’s voice grew tense as he went on. "But what a setup! If that undersea layout is really built of solid gold, it must be worth more than Fort Knox!"

Surprised by the officer’s greedy tone, Tom retorted, "We’re not going as gold prospectors, Lieutenant. That lost city may hold the answers to a whole flock of historical and geological problems!"

"Well, I’m all for science," was the reply, a bit sarcastic. "I take it you’ll be retrieving some artifacts and specimens to take back."

"Yes, a few. We need a clearer idea of what we’re dealing with here. But the main purpose is to map out the site."

"Yeah. You need to figure where to set up that bubble machine of yours."

It was Tom’s plan to use his matter-repelling device, the repelatron, to push back the waters and create a giant bubble, or series of bubbles, over large areas of the city. The scientists would be able to live in these air-filled hydrodomes in a comfortable shirtsleeve environment without the encumbrance of bulky protective suits. He had used the same method to establish his permanent helium-mining facility.

Further conversation was forestalled by a low cry from Slim Davis. "There it is, Tom. That must be the pass the Arrow went through last time."

"It sure looks familiar," Bud commented. "I don’t remember it being so narrow, though."

"Don’t forget, flyboy—that avalanche brought down a lot of rock," Tom pointed out as he studied the broken cliffside. "Anyway, we always knew the Deepwing would never be able to work its way through."

"I know that’s the plan, but still—" The young pilot’s brow creased beneath his straggling lock of dark hair. "Isn’t the upper route pretty much blocked off?"

Cromwell glanced at Tom with narrowed eyes. "Blocked off? What’s he referring to?"

Tom gave the Navy officer a muted look of surprise. Just what had the man been briefed on? "The city sits on the floor of a sort of narrow box canyon with a single outlet, the pass. It’s completely surrounded by very high, steep cliffs. The opening at the top comes in at a slant—sort’ve like the chute on a mailbox, if you see what I mean. The overhang shields the ruins from sight, including sonar depth-mapping and imaging."

Cromwell nodded. "Got it. So now we slide down that chute."

"I’d prefer keeping an even keel to sliding," Tom responded curtly.

He now directed Slim to slightly decrease the rate of the rotors. The mantacopter bobbed upward gently, and the jagged side of the barrier cliff slid downward across the viewpane past their watchful eyes. As Zimby read off numbers from the sonarscope, Slim deftly guided the craft forward over the top spine of the seamount, then followed its slope downward again.

Tom pointed. "That way. About twenty degrees to portside."

"Just what are you aiming at, skipper?" asked Bud. "I don’t see any opening at all."

"Look at that forest of seaweed," directed his pal. "I’m sure it’s covering the entrance. Sonar says it isn’t very dense. We can’t see through it, but I’m betting we can push through it without difficulty."

The Enterprises personnel all trusted Tom’s instincts and scientific judgment, but it was impossible not to feel a surge of anxiety as the Deepwing edged its way into the screen of indigo streamers. Yet there was no jolt, no impact. The waving vegetation crawled lazily across the window of Tomaquartz, then parted before them like a curtain. They had made it through!

Cromwell muttered, "Now that wasn’t so hard, was it?"

The sub was now moving through an open space beneath a down-tilting rock ceiling. The aqualamp revealed a corresponding slope beneath them, and walls that faded off into the dim distance. "Big as a football field!" Bud breathed.

"And it widens out below. The actual canyon floor, the site of the ruins, is at least a mile across," Tom reminded him. "Just imagine the sort of tremendous upheaval that shattered these slabs of ocean bedrock and forced the fragments up on end!"

Obviously unimpressed, Lieutenant Cromwell noted that the slope fell off into darkness one hundred yards ahead. "Must be the edge of the canyon, hmm?"

The mantacopter sailed over the edge, then paused, hanging in watery space as Tom switched on the hull-bottom aqualamp and angled it sharply downward. Grinning but silent, he gestured broadly as the crew craned their necks.

"Lord above!" gasped Zimby Cox. "It’s fantastic!"

The electronic gleam lit the floor of the subocean canyon like a miniature sun. The submarine city, crumbling and overgrown but clearly visible, spread out in all directions. They could see square and circular structures, collapsed towers, traces of broken columns, scattered blocks of worked stone, and small upthrust objects that might prove to be statues or monuments. The pattern of streets was still evident to the eye.

Cromwell interrupted the moment of stunned reverie. "Looks more brown and green than gold."

Tom stared at him disapprovingly. "The real surfaces, gold or not, are underneath all that accumulated gunk. In fact, clearing it away is the purpose of a new invention that we’ll be freighting along when we come back to set up operations."

As Slim brought the Deepwing down into the maw of the canyon, Zimby half-turned to Tom and said, "Skipper, I meant to tell you—you might want to take a look at Hatchway Four."

"Something wrong?"

"Not necessarily. But when I was checking out the airlock sequencing controller, there was a little fluctuation in the circuit. It straightened itself out almost immediately, but I thought I’d mention it."

"Thanks, Zim. C’mon, Bud, let’s take a look."

As Tom led Bud through the corridor to the starboard hold, he said quietly, "Lieutenant Cromwell doesn’t seem to have absorbed his briefings very well, has he."

"My thoughts exactly," Bud agreed. "Of course, with different words!"

"He sure seems focused on the gold," Tom added as he entered the hold, which on this preliminary trip was mostly empty. Popping the reinforced door, the youths stepped into the large freight airlock adjoining Hatchway Four.

Tom removed a small circuit-scanner from his pocket and approached a green rectangle painted on the bulkhead. "The main circuitry is here, behind the wall," he explained to Bud. "There’s no actual access port, because we don’t want to introduce a weak point in—"

He interrupted himself as the overhead lights seemed to dim slightly, then returned to full power. "What’s up with that?" Bud asked, looking toward the ceiling nervously.

But Tom had no time to answer. He whirled, startled, as the open door to the hold swung itself shut behind them with a bang. A hissing sound, painfully high-pitched, suddenly filled the chamber, causing the two to wince. As they staggered back in bewilderment, thin jets of water shot downward like crystalline rods from a dozen small openings where the surrounding walls met the ceiling. A spray, rebounding from the airlock deck under tremendous pressure, hit them from all sides with a stinging impact.

"Good gosh!" Tom murmured in horrified disbelief. "The airlock’s being flooded!"

"Not from inside! But maybe the door hasn’t sealed itself."

They sloshed to the door and grabbed its heavy metal handle with four desperate hands. Pressing their feet against the bulkhead, they pulled together with all their strength. Their muscles bulged and the veins in their necks stood out, but the door held. "It’s sealed," Tom panted. "The whole automatic airlock sequence must be running. When we’re flooded to the top, the outer hatch will open."

"Can’t we stop it?" gasped Bud. "Rip out some wires or something?" His eyes darted about frantically. "But no—no access panels, no controls. Aw jetz, Tom!"

Their legs were growing numb as the frothing water rose above their knees. Suddenly Tom grabbed Bud’s arm. "Your shoes! Take them off!"

The young pilot boggled. "Don’t go nuts on me now, Tom!"

"Do it! Hurry! Hand ’em to me!"

Bud complied. The direct contact of the water with his socks made no difference—his feet were as feelingless as lead weights. But plunging his arms and upper body into the freezing water shocked his system from head to toe.

Tom also had ripped off his shoes. He waddled over to one corner, gazing up at the spot where two walls met the ceiling. There the surface was interrupted by an oval opening about the size of two fists. "Boost me up, Bud," he commanded. As Bud did so, Tom pounded first one shoe, then a second, into the opening, one above the other. Almost immediately the youths winced in pain as a jolt of air pressure surged against their eardrums. "Now the other vent!" Tom gasped.

In a moment both oval openings were crammed full of shoe. Tom and Bud pressed their palms over their ears, their eyes slitted with agony. "The rising water is compressing the air," Tom yelled. "We’ve blocked the air outlet ports."

"So now what?" Bud demanded. "Will the backpressure hold back the water?"

"Eventually!" But Bud grasped the implication. By the time the pressures came into balance, they would be dead! Nevertheless, the rise of the water slowed as the airspace above it shrank. The water was knocking against their chins as they stood on tiptoe, shivering violently and barely holding on to consciousness.

Then, without warning, the water inlet jets choked off. The reassuring sound of pumps reverberated through the chamber as the water level began to fall away. In two minutes they were high and dry, lying on the deck and gasping for breath.

With a click the inner door popped open, and they dragged themselves into the hold. As they lay panting, Bud choked out, "Wh-what happened?"

"As I hoped... when the ports couldn’t drain off the air and the pressure got too high... the safety backups overrode the controller circuit..."

Bud shook his head, starting to breath normally again. "Great. But what I meant was, what made the circuit go bad in the first place? Sabotage?"

Tom shrugged, but his shrug was an eloquent answer in itself. They both were well aware that their official passenger had spent much of the trip in the rear of the subship, out of sight.

In the pilot’s cabin the other three members of the crew were horrified. "You mean you guys were getting yourselves drowned and crushed back there, and we didn’t have a clue?" gulped Slim Davis.

"I would think some kind of emergency alarm would have gone off," declared Lieutenant Cromwell.

"It should have," said Zimby. "Definitely! It must all be due to that circuitry problem I noticed."

Tom looked out the viewport musingly. "That seems likely. We might have jarred a weak connection when we opened the inner door to go inside. We’ll check it out back in port."

"Back in port? You won’t be completing your survey, then?" demanded Cromwell.

Tom did not respond, but spent a minute checking over the system readouts on the control board. "Nothing else looks suspicious," he stated at last. "We’ll proceed for now."

"It’s your call," Cromwell said indifferently.

Slim Davis had set down the Deepwing in a fairly open space that might have been a plaza at the intersection of two boulevards. The mantacopter rested upon flexible tractor treads that extended from the under-hull on pistons.

Zimby asked if Tom and Bud were about to go outside. "A little later, Zim," Tom answered. "It’s really more important to get the mapping done." As he spoke the young inventor was watching Lieutenant Cromwell’s expression from the corner of his eye. Was the man’s frown only Tom’s imagination?

Lifting off to a height of about fifty yards, Slim guided the Deepwing along an expanding spiral course, using doppler sonar to map out the lay of the ruins. In an hour they had surveyed the entirety of the city and were elbowing along the cliffs and rocky slopes that surrounded it. Landing again near a complex of big, tumbled structures, Tom and Bud made ready to exit the craft.

Cromwell held up a hand. "Just the two of you?"

"Got a problem with that, Lieutenant?" snapped Bud in a challenging voice.

But Tom spoke soothingly. "It’s his assignment to keep an eye on us, Bud. You’re welcome to join us, sir, if you like. It’s easy to get the hang of the Fat Man suits."

Tom led Bud and Cromwell down a short corridor abutting the hull, stopping where four man-sized metal objects, polished to a silver shine, protruded from the bulkhead as if penetrating right through the ship’s hull. These were the Fat Man suits, midget one-man submersibles that made their way along on jointed mechanical legs. Each suit was equipped with small propulsion jets, robotic arms, and its own independent air supply.

Lieutenant Cromwell gave the suits a skeptical lookover. "You don’t keep them in an airlock?"

"It’s not necessary," Tom explained. "Each suit fits perfectly into an opening in the hull lined with a contoured sealer-flange that can withstand pressures as well as the hull itself. They face inward, with the backside protruding out into the water. As you back away and disconnect, the flange dilates inward along the curve of the suit and closes off the hole. Not a drop leaks through."

"No doubt you’ve tested it out thoroughly," the officer grunted. "Then again, I had assumed the same thing about your airlock." Ignoring the dig, Tom demonstrated how the entire inward-facing half of the Fat Man swung open like a door, allowing the aquanaut to step backwards into the suit. Pulled shut, it would seal itself automatically.

As Cromwell turned to enter his Fat Man, Tom held his hands behind him, out of sight to the Navy man but in full view of Bud. Waggling his fingers to attract his friend’s eye, Tom signed a silent message in ASL, American Sign Language. Hang back, don’t seal. Bud coughed, signaling that he understood.

After a few minutes of instruction, Tom swung the suit closed on Cromwell, at the same time surreptitiously opening a small panel and twisting some control knobs beneath it. "All right, Lieutenant. You can switch on the flange release mechanism and start backing out."

Behind the transparent viewdome Cromwell gave a curt nod and his thick-fingered hands moved about on the small control panel before him. "Nothing’s happening," he muttered over the suit’s external speaker.

"I’ll go over it with you again," was Tom’s response. But when he made a show of unsealing the front of the suit, it refused to open!

"What the blazes is wrong, Swift?" demanded Cromwell with rising anger and a trace of panic. "I want out of this thing!"

Calling Bud over—and giving a secret wink—Tom and his chum worked at the problem for several minutes as Lieutenant Cromwell’s face grew redder and oilier. Finally Tom looked up and shook his head. "I’m sorry, Lieutenant. Some part of the mechanism is malfunctioning. I can’t open her up without special tools. But it’s a good thing the problem showed itself while you were still inside the Deepwing—I hate to think—"

"Are you trying to tell me I’m trapped inside this can?" Cromwell interrupted furiously.

"You’re perfectly safe. The air tanks will last until we return to base. We’ll leave immediately, of course."

"Just pull down that little seat behind you, Darrin old boy," put in Bud with a twitch of a mischievous smile. "Take a load off."

The boys turned and hastened up the corridor, leaving Cromwell raging and sputtering behind them. Back in the control cabin, Bud slapped Tom on the back. "Mighty sweet deal, genius boy!" he laughed.

"What’s going on?" asked Zimby.

"We’ve got our mapping data. We’re done here for now. Slim, take us up and out—let’s head home," Tom answered smoothly.

Both Zimby and Slim looked startled. "But why? Where’s Cromwell?" asked Slim.

"In safekeeping."

"In a cool dry place," Bud added. "Should keep fresh for hours."

The mantacopter angled back up through the slot and into open water, then rose the long way to the surface. Slim reversed the pitch of the rotor blades and the Deepwing lifted several yards above the low waves, suspended on a cushion of compressed air. Soon they were jetting south of west toward the Enterprises facility on tiny Fearing Island off the coast of Georgia, base for the company’s space missions and many of its unique submersibles.

Tom made numerous attempts to contact Fearing, then Swift Enterprises in Shopton, New York. But the radio replies were garbled, fading, and full of harsh static. "That upper-air storm must be putting out a lot of lightning," was Tom’s analysis. "Anyway, our saboteur—our suspected saboteur—won’t be going anywhere until we have a chance to get Security involved."

"But what could the guy have been after?" asked Slim Davis. "Why try to get rid of you two? Is he some kind of foreign spy?"

Tom shrugged. "Beats me. He arrived with all credentials in order, and both Admiral Hopkins and Admiral Krevitt spoke highly of him."

"Maybe so, but my instincts are going off like a four-alarm fire!" Bud declared.

Finally settling into the seacopter dock at Fearing, Tom briefly stuck his head out through one of the small personnel hatches and directed the dock crew to bring an armed security team on the double. When he saw the team approaching by jeep, he went back below.

Cromwell was still red and fuming in his metal egg, but his voice was under control. "We there? Got your tools?"

Tom nodded without speaking and crouched down out of sight. Again twisting the external suit control knobs, he stood up and pulled the suit hatch open. "That did it. Bet you’d like some fresh air up topside."

The man only glared. As they walked briskly past Bud and the others in the control cabin, the young flyer asked softly: "Any special orders for the crew, skipper?"

Tom shook his head, keeping his eye on Lieutenant Cromwell, who had practically run across the deck to the hatch ladder. "It’s Rad’s show," he whispered. Phil Radnor, assistant security chief of Swift Enterprises, was making a week-long inspection tour of the Fearing Island security setup.

Tom and Bud followed Cromwell through the hatch. As they trotted down the rampway to the concrete dock, Tom tensed. Radnor awaited them with crossed arms, a burly Fearing security man at either side, hands resting lightly on their holsters.

To Tom’s surprise, Radnor stepped forward and extended a hand toward Lieutenant Cromwell, who glanced at it as if it were a snake, but shook it. "Phil Radnor," said the stocky security man with a friendly smile. "Pleased to meet you, Mr. Judson. You’re under arrest."

The man in Navy uniform jerked away his hand. "What’s that? Arrest?" He spat out the words, eyes darting wildly. "You’re crazy! I’m—"

"Joe Judson, right arm to Longneck Ebber," said Radnor coolly, motioning his two men forward. In an instant Judson, the phony Cromwell, was handcuffed. "This is where you say things like This is an outrage. But spare our ears, okay, Judson?"

The man fell silent. Tom turned to the assistant security chief and gestured toward the prisoner. "Who is this man, Rad, and what’s his full name?"

"Not Darrin Cromwell," was Radnor’s grim response. "The real one was kidnapped, along with his Navy pilot, during their Washington stopover en route to Enterprises. They were pistol-whipped and held captive until four hours ago when Federal agents tracked them down. They’re hospitalized. So’s your buddy Dick Halfven, Joe—two bullet wounds. And we’re on the trail of the guy who posed as your pilot."

"Okay, but who are they?" Bud demanded. "What’s the deal?"

"We don’t know the deal," said Radnor as Judson was carted off by jeep. "Ebber runs a branch of something called the Mayday Mob. Wise guys—mobsters."

"The Mafia?" Tom inquired.

"No, independents with plenty of nerve and plenty-thick skulls. Or at least that’s their rep—independent practitioners of the fine art of organized crime. But the Feds think they have some new backers. And that’s bad news for you, boss—and for your Atlantis operation!"

"Don’t forget the gold," noted Tom wryly.

But Radnor shook his head. "I’m sure that sweetens the deal for Ebber and company, but Harlan’s contacts are pretty sure a foreign government is involved." Harlan Ames, a former Secret Service agent, was head of Swift Enterprises security.

"Brungaria?"

Rad chuckled. "Nope, the other one—Kranjovia!"

When Tom and his team had travelled to Antarctica to drill for molten iron with his atomic earth blaster, he had been stalked by agents of the Democratic Workers Republic of Kranjovia, a splinter of dictatorship located on the Baltic Sea. The government there had proven a ruthless and persistent foe of the United States and other modern democracies. "What are Kranjovia’s interests regarding the submarine city?" the young inventor asked as they began strolling from the dock in the direction of the huddle of buildings fronting the spaceport and island airfield.

"Again, no one really knows," stated Radnor. "But they’ve been privy to the same closed-door discussions as other European nations, and I understand they’ve raised quite a few official objections to the American interpretation of various agreements and treaties—loud, strenuous, and threatening objections!"

"Uh huh, that’s Kranjovia all right," snarled Bud in disgust. "They never met a civilized nation they didn’t dislike."

But Tom disagreed with his pal. "The problem isn’t the country but their self-appointed dictator, Ulvo Maurig, General-Secretary of the Party. Some of his government officers are fairly sophisticated, but Maurig is supposed to be some sort of delusional egomaniac."

"And today’s mystery question is—just what sort of delusion does he have in mind?" Phil Radnor snorted.

After seeing to the berthing of the Deepwing, Tom and the others were jetted back to Shopton by Slim Davis while Judson remained under lock and key on Fearing Island, awaiting the Federal agents who would transport him to his fate. He had sullenly refused all further comment.

It was early evening when the scientific travellers deplaned onto the broad airfield of Swift Enterprises, whose ultramodern installation was four miles on a side. Tom and Bud joined Tom’s father in their shared office. The elder scientist had already been briefed by radio, the lightning storm having finally drifted away. Harlan Ames also joined them.

"Phil Radnor did his usual superb job, Harlan, commented Damon Swift. His voice was faint. The description of the terrifying threat to his son’s life had shaken him deeply.

"We expect nothing less of each other," Ames responded. "Are you all clear on the sequence of events? From the description provided by the real Lieutenant Cromwell, the FBI was able to identify the kidnapper as an ex-convict with known ties to Ebber and his mobsters. Judson has already served time for embezzlement, firearm violations, even second-story work. He carried out the assault on Cromwell and the Navy pilot with a pal who we think is named Gilly Murchison, a former military pilot gone bad. That’s all we know so far. No sign of Murchison or the hijacked jet."

"What about the big boss?" Bud spoke up.

"Ebber is still at large," Ames replied. "It seems he’s always at large—for years now. Never quite enough evidence to nab him. But he may not be for long, after the authorities start tracing his contacts with Kranjovia."

"If Judson was working for foreign agents," Mr. Swift said, "we may be in for serious trouble. Ulvo Maurig is a sort of gangster himself, and his cadre is absolutely ruthless. We know that from the Antarctica business."

"Well, I think they must be running out of ideas," noted Tom with a weak smile. "This is the second time they’ve used the drowning bit on Bud and I."

"They say the third time’s the—" Bud began.

"Don’t say it," snapped Mr. Swift sternly.

The distinguished scientist’s face was grave as he outlined the possible dangers. "Once other nations find reason to doubt America’s ability to manage and protect the site, they’ll mount a diplomatic full court press to internationalize any scientific presence there."

Tom sighed. "It would be like a horde of sightseers trampling around at a crime scene. The clues science is counting on could be compromised, or lost altogether. The gold doesn’t matter at all compared to that."

The meeting concluded, Tom left the office for one of his private labs, telling his father that he would be home for a late family dinner after downloading and checking the sonar mapping information from the trip, which he had carried to Enterprises on a computer disk.

He left the plant a few minutes later and began to head home in his two-seater sports car. Noting that there was still plenty of time before dinner, he decided to follow a winding route that led through the pleasant woodlands that rolled along at the edge of Lake Carlopa for most of the distance around the lake. Though he had tried not to show it to his father, Tom himself had been deeply affected by his horrifying experience in the airlock. He felt a need to unwind, and always found the scenery refreshing after a hard day’s work at the plant.

Man! That pine-scented air sure smells good! he thought, breathing in deeply.

Glancing at the rearview mirror, Tom noticed headlights some distance back on the unlighted road, which was little used by locals and often completely deserted. On impulse he pulled to the side of the road and allowed the other car to catch up and pass.

"A new Tioga," he noted admiringly. "That car has a real engine for a compact job!"

Taking to the road again, Tom’s thoughts soon turned to his own problems. What was behind Judson’s actions? What orders had the Kranjovians given him? Were other plotters at work to stop him from exploring the city of gold?

Tom was still deep in thought several minutes later when, rounding a curve, he started violently as a figure came staggering out of the trees ahead and into the roadway almost directly in front of him! He slammed on the brakes and screeched to a breathless stop as the figure, a middle-aged woman, collapsed to her knees beside the pavement. Leaping from the car and running up to her, Tom was shocked to see that she was bleeding from a wide gash on her forehead.

"Please... please... we need help!" she gasped. "Our car—"

She gestured weakly. Tom noticed for the first time signs of a skid leading into crushed, flattened shrubbery. "I’ve got to get you to a hospital," he said comfortingly. "I can call an ambulance on my car phone."

"No, please," she sobbed, "I’ll be all right, but Harry—he went right into the windshield, and—and I don’t think he can pull himself free. You’ve got to..." Her voice trailed off as if she were on the verge of fainting.

"I’ll take a look," Tom assured her. "You’d better lie flat." He followed the smashed bushes and scarred tree trunks down a gentle slope for about fifty paces. Then, in a clearing, he saw a car butted up against a tree.

The Tioga! his mind registered. But as he trotted closer, he hesitated, puzzled. The windshield was undamaged, and there was no sign of anyone inside the car.

Immersed in the problem, his keen mind blotted out the rest of the world—and then went dark as he was struck violently from behind!

"Mm! That smells heavenly!" Sandy exclaimed, coming back to the kitchen. "You are positively the best cook in seven counties, Mother!"

Anne Swift, a slender, attractive woman, gave her daughter a hug. "You’re a flatterer, dear. But thanks!"

"I mean it—really," Sandy insisted. "Dad says you’ve spoiled us for any servant’s cooking and he’s right. It’s your own fault!"

"I like cooking for my own family—it’s a joy!" Mrs. Swift said. "That’s why I do it. It isn’t just the men who have the inventive instinct, you know."

As they proceeded with the preparations for the late-evening dinner, Mr. Swift ambled into the kitchen, a scientific journal in hand. "Now I’m relaxed," he joked. "By the way, where’s Tom? Not home yet?"

"No. In fact I’m getting worried," Mrs. Swift fretted. "You said he had only planned to work a while longer, but it’s been—"

Mr. Swift glanced at his watch. "Well, you know how absorbed Tom gets." The scientist smiled. "Arv Hanson finished the scale model of Tom’s new invention. He’s probably caught up in working out some kink." Arvid Hanson produced working models that usually served as preliminary test prototypes for Tom’s inventions.

Anne Swift shook her head distractedly. "No, it can’t be that. He showed me the model here at home just before he left on his underwater trip."

Sharing in the concern but feigning a nonchalant attitude, Sandy put the finishing touches to the table setting. The roast and vegetables were soon ready and the Swifts decided to eat. But after a few halfhearted bites, Mr. Swift said, "I think perhaps I’ll call the plant and jog Tom’s memory. We can keep his plate warm if we know he’ll be home soon."

From the telephone alcove in the hallway he called Swift Enterprises on their private line. The night operator rang Tom’s laboratory and then the double office in the main building. Neither call drew an answer. Next she paged the young inventor over the plant’s public-address system—again without success.

"I’m sorry, sir," the operator reported. "Your son must have left."

After trying Tom’s personal cellphone and the unit in his sports car, Mr. Swift called Bud at his apartment in town. "Sorry to disturb you, Bud," the scientist said pleasantly when the young copilot answered the phone. "Tom hasn’t come home yet and I wondered if you’d seen him."

"Why no, sir. Not since the meeting in your office," Bud replied. "Think there’s something wrong?"

Mr. Swift hesitated, seeking unalarming words. Bud sensed his uneasiness, a feeling he began to share. "Mr. Swift, let me get hold of Harlan Ames. I’ll call back as soon as possible."

"Thanks, Bud. I’m sure it’s nothing."

Mr. Swift returned to the dining room, trying to conceal his inner concern. But his wife’s eyes met those of the inventor in a worried look. "Damon, is Tom all right?" she asked anxiously. Her husband replied reassuringly, "So far I can’t reach him, but we’ll no doubt hear from him soon. I wish I had a dollar for every time Tom has been late."

All three waited worriedly in the big comfortable living room. Tense moments crept by. When the telephone rang, Mr. Swift sprang up immediately to answer it. "This is Bud," the caller said. "I talked to Ames and he thinks we’d better start a search. Would it upset Mrs. Swift if we dropped over and talked about it?"

"Come ahead, Bud!" the scientist replied. "I’m afraid she’s already upset."

A few minutes later Bud’s sleek convertible pulled up the graveled drive. On the way he had picked up Arv Hanson, a big blond six-footer. Ames arrived shortly afterward, bringing Slim Davis and Hank Sterling, the quiet-spoken, hard-fisted chief engineer of Enterprises, a close friend of the family.

"No news?" Mr. Swift greeted the new arrivals at the front door.

"Not yet," Ames replied, then whispered, "We’re afraid that Tom’s absence may be connected with the arrest today of Judson." The security chief walked into the living room and was greeted by Tom’s mother and sister. He asked, "Can you think of any errand that might have taken Tom out of his way?"

The Swifts shook their heads to both questions. "Then," Ames went on, "we’d better divide into search parties and cover every route Tom may have taken from the plant. If that doesn’t turn up any clues, I think we’d better call in the police."

"Shouldn’t Mother and I go along?" asked Sandy.

"Let’s stay home and wait for Tom," Mrs. Swift said. "He could arrive any minute."

After a hurried conference to settle their plan of action, Bud took off in his convertible with Arv Hanson. Ames went with Slim Davis. Mr. Swift followed in his own car, accompanied by Hank Sterling.

Fanning out through Shopton, they questioned traffic policemen, news vendors, and gas station operators—anyone who might have noticed the young inventor’s custom-built sports car, very well known throughout the town.

Remembering some previous incidents, Mr. Swift drove over the tree-shaded lane which he and Tom sometimes used when they felt like walking home from the plant. The other two cars took the main highway which led from the outskirts of Shopton past Enterprises. All reported failure when they met at the plant.

Mr. Swift was tight-lipped but calm. "Tom occasionally takes the old Mansburg road around Lake Carlopa," he recalled.

"That’s right," Bud confirmed. "He takes it when he has some thinking to do. Let’s give it a try."

To make use of all six pairs of eyes, the three cars set off together, using spotlights from Enterprises to illumine both sides of the wooded road.

Ames was in the lead. Suddenly his car swerved toward the dirt shoulder and braked to a halt.

"Hold it!" he called via cellphone. "I see something!" What looked to be an automobile windshield was gleaming among the trees. The others braked their cars to a stop and leapt out.

"It’s Tom’s car, all right!" Bud cried. "But where is he?"

"Look over here, guys!" yelled Hank Sterling. The pooled spotlights showed tire tracks and an oil stain where a car had evidently swerved off the pavement. Crushed underbrush pointed a further route among the trees.

Mr. Swift went pale. "He may have been forced off the road by a second car!" he murmured. "If they pulled a gun on him—!"

Hank Sterling gripped Mr. Swift’s arm. "Maybe you’d better stay here, Damon."

But with his son’s fate in question, nothing could stop the elder scientist. All six grabbed powerful flashlights from the cars and hurried into the darkness of the woods.

The trail ended in a clearing next to a ravine that was almost invisible behind a wall of overhanging trees. Tracks, gouges, and oil droplets gave testimony that a vehicle had been parked there recently. "Oh, no!" A tense cry escaped Bud’s lips as he pointed off beyond the clearing. Broken branches showed that something or someone had made its way through tangled underbrush edging the ravine!

Had it walked—or had it been dragged?

Sick with fear, the searchers scrambled down the sloping bank, Bud and Mr. Swift in the lead. "Maybe Tom was dazed by the accident," Bud suggested hopefully. "Perhaps he’s wandering around somewhere close by!"

Mr. Swift was in no mood for false hope. "There was no sign of an accident, Bud."

"Tom! Tom Swift!" The repeated calls rang through the darkness.

Suddenly a yell from Bud electrified his companions. Within moments all of them had rushed to his side. Ames arrived last and gave a startled gasp.

Tom lay unconscious on the ground, caked and drying blood on the back of his head and neck. His father knelt beside him. The glow of their flashlights revealed a square white object, like a card, pinned to his t-shirt.

Mr. Swift scarcely trusted himself to speak. He gestured that someone should look at the note.

"No words," grated Ames. "Just some kind of figures or symbols."

"Figure it out later!" Bud commanded. "We’ve got to get Tom to a hospital!"

Mr. Swift had slipped one arm under Tom’s shoulders. "He’s had a blow to the head, obviously," he muttered after a quick examination. "No sign of anything else. He’s breathing—strong pulse."

Suddenly Tom sucked in his breath. "He’s coming around," said Slim Davis.

The young inventor’s blue eyes fluttered open. He blinked at the faces bending over him.

"Tom! Do you recognize us?" Bud asked, his voice quavering.

"Sure I do," Tom breathed. "You’re Sandy—right?"

Bud snorted in joy and relief. "He’s fine!"

Presently Tom recovered enough to tell what had happened. "Did you get any glimpse of the person who hit you?" Ames inquired.

Tom shook his head painfully. "No. But it must have been the driver of that Tioga. I’m sure the woman was his crony—a real actress."

"Did you notice the license plate?" asked Arv Hanson.

"I’m afraid not."

When Ames showed him the strange note, Tom looked it over and frowned thoughtfully. "These two symbols look like Chinese writing. It must be some kind of warning or threat."

"Whatever the point of it was, they didn’t intend to kill you, it seems, thank God," said Tom’s father.

"Hey!" shouted Hank Sterling, who had strode a few paces away. "There’s something further on down the slope!"

Ames trotted over. His sharp eyes followed Hank’s pointing finger.

"It’s a body," he pronounced grimly.

Ames worked his way down the side of the ravine about fifteen feet further. "Male caucasian, early middle age, balding." He spoke loudly enough for the others to hear. "Unarmed. No wallet. And very dead." He stood and climbed back to the others, rejoining Tom and Mr. Swift. "He was shot, then picked up and tossed down the embankment."

"Oh man," said Bud. "Must’ve been an innocent bystander who saw too much."

But Ames shook his head. "Not the way I read it. Near the body is a short length of copper pipe—probably what he used on the back of that concrete skull of yours, Tom. There was a little grease on the pipe, and the guy had the same stuff on his right palm."

"It could be a ruse," Tom said, "but it sure looks like the victim was the man who attacked me."

"Then what the heck’s going on?" exclaimed Slim. "Two teams fighting each other to take out Tom Swift?"

"Forget all that right now," demanded Tom’s father impatiently. "I’m driving Tom to Shopton Memorial."

"I’ll switch seats with you, Bud," offered Hank Sterling. "Go along with Tom. We’ll all wait for you back at the house."

Hank and Slim half-carried the young inventor back to his father’s car. Mr. Swift rushed Tom to Shopton’s main hospital. Slim Davis volunteered to drive Tom’s car back to the Swift residence.

Almost before Mrs. Swift and Sandy had had time to absorb the distressing series of events, Tom was back home, head bandaged but in good spirits. The doctors had pronounced him free of concussion, but prescribed, sternly, two full days of bedrest,

It was a daunting prescription for Tom Swift. By morning he felt fine and was bursting with energy. He greeted his mother and sister with a smile as he sat down to a late breakfast. Mr. Swift had already left.

"Please stay at home today," Mrs. Swift urged anxiously.

"Can’t, Mom! Honestly!" Tom grinned and hugged her. "But I promise I’ll—"

"Darling, when I said ‘please’ I was just being polite," said Mrs. Swift sweetly. "I’m prepared to use strong-arm tactics if necessary."

Tom gave her a sheepish look. "Gee, I think I’ll head back to bed. I’m feeling just a little—faint."

"I have such smart children."

As the restless invalid lay in bed reading, his nightstand telephone rang. Harlan Ames was calling. After asking Tom how he felt, Ames said, "I thought you might like to hear the report I just gave your Dad. The police and the coroner have confirmed what I said about the man’s death. They’ve run fingerprints and dentals; it seems our late friend was one Gilly Murchison, a gangster, somewhat low in the food chain."

"That’s the man suspected of playing pilot for Judson."

"Yes. I’m sure Joe will be broken up, losing a pal like that. We haven’t had any luck tracing the woman or the Tioga. And guess what?—the bullets used on Gilly were expertly plucked out of his body, so there are no leads in that direction."

"What about the note, Harlan?"

"Nothing unusual about the paper. Just a blank for a business card print run. No fingerprints, of course. But we do have a lead, or at least something interesting to consider."

"The writing?"

"Right. That was a good hunch of yours, about its being Chinese. We took it over to Arv’s assistant, Linda Ming. It’s a little weird and a lot melodramatic, Tom."

Tom laughed. "Always is!" He listened with keen interest as the security chief continued.

"One symbol was easy. It means Death. The other was unusual. Linda thinks it’s the ideogram for a man’s name, Li Ching. But it’s been stylized in a funny way—looks a bit like a snake."

"It must be his trademark, so to speak," Tom mused. "Does that name mean anything to the authorities?"

"He’s not a wanted criminal, not in the US anyway," replied Ames. "But they’re looking into the possibility of a foreign connection. I’ll let you know if anything pops up." He added that Joe Judson, now in Federal custody, had been interrogated. "But it was a waste of effort," Ames concluded. "Judson still won’t talk."

Tom mulled this over. "Hmm. Maybe if Longneck Ebber is found, it’ll solve the mystery."

"I hope so," Ames said glumly. "But the FBI has no lead on him yet. He seems to have dropped out of sight."

Shortly after Ames’s call, Doc Simpson, the young Enterprises physician, arrived at the house to perform his own examination of Tom. He firmly ordered Tom to remain in bed. "No use pleading, boss," the medic said. "That was a nasty blow you got, concussion or no. If you overdo things, it could have some aftereffects. Now you stay in bed and take it easy—at least for today."

Tom fumed but complied, secretly thinking: Well, at least I’ve shaved one day off my captivity! Sandy did her best to keep her brother amused throughout the day. But it was hard for someone as keen and active as Tom to stay cooped up like an invalid when he felt well and sunshine was pouring through the upstairs windows. Besides, there was so much to be done on the undersea project!

Fortunately Bud stopped by during the afternoon, bringing Bashalli Prandit in his red convertible. Bashalli was Tom’s favorite date—in fact, his only regular companion among the eager young ladies of Shopton.

"What a break!" he exclaimed with a grin. Bash’s dark eyes twinkled as she produced a gift she and Bud had brought. "I think the major break was to your skull. But here, Thomas—get well soon!"

She held out a tempting basket of glazed fruits and other delicacies.

"Wow! This is worth having to stay in bed for!" Tom chuckled with delight at the girl’s thoughtfulness. "Thanks a million, you two!"

"We’ll help you eat it," Sandy volunteered. Tom tore off the cellophane and passed the basket around. As they nibbled the fruits, Bashalli asked how Tom had been passing the time. "Other than recuperating in bed—which you do seem to do quite a lot, I must point out."

"He beat me so often at chess that he got bored," Sandy replied. She giggled. "Then he started working out theorems in rubber-sheet geometry."

"Good night, what’s that?" Bud asked.

"Don’t ask me!" Sandy retorted mischievously. "He says it deals with such problems as whether the hole is inside or outside of a doughnut."

Tom laughed at Bud’s popeyed stare. "The real name for it is topology, a form of mathematical analysis having to do with shape. It’s a little tough to explain."

"Okay! Don’t bother," said Bud hastily with a wink in Sandy’s direction. "I suppose it has something to do with your cannon."

Bash’s eyebrows arched prettily beneath her raven-black hair. "Tom has invented a cannon?"

"Oh, that’s just what Bud calls it, Bashi," explained Sandy with a teasing roll of the eyes. "Look, there’s the working model right over there."

Bashalli curiously examined the intricate miniature resting upon Tom’s desk. "I see. It does look a bit like a cannon, doesn’t it."

"It’s called a spectromarine selector," Tom said with a smile, half-apologetic over the somewhat tongue-twisty name.

The device sat upon a rectangular platform with small tractor-tread units attached beneath. "The full-sized version will be twenty feet long and eight feet across," the young inventor explained, "and the tread units will be able to be extended downward on pistons to accommodate uneven terrain, just like the ones on the seacopters."

Bashalli pointed to the silver, cannonlike unit swivel-mounted on a pedestal and pointing forward. "And this fearsome cannon—what is it for, protection against whales?"

Tom broke out laughing, then winced, touching the bandages around his head. "I’ll tell you all about it, ladies—Bud’s already had his usual briefing. First of all, the purpose of the spectrosel is to help marine archaeologists, which is a specialized profession nowadays, explore subocean ruins by safely and selectively cleaning off the thick coatings of gunk that accumulate over the centuries. Most of it consists of organic remains: dead seaweed, layers of plankton, coral—that sort of thing."

"Maybe a few leftover tentacles from a dead octopus," Bud put in.

"And pirate bones," Sandy added.

"All right, then," said Bashalli. "And so, how does this de-organic-izer of yours actually work?"

"Look, I’ll show you the main components." Bash handed Tom the model. "These little units mounted above and below the mouth of the ‘cannon’ are synchro-phased masers—microwave lasers. They produce two focused beams. You can stand in front of them and barely feel a thing, but at the point where they combine, right on the surface of the material to be removed, a real hotspot is created."

"Since you’re talking about waterlogged stuff, that must cause steam," Sandy remarked.

"Yep. In fact it causes a tiny explosion of steam at the point of focus, strong enough to peel off the outermost layer and literally blast it away into the air. As the beams scan back and forth, the entire underlying surface will eventually be exposed."

Bashalli shrugged. "Very nice, but you will have quite a pile of debris to sweep up, even if it has been steam-cleaned."

"Not at all, Bash," responded the youthful scientist-inventor. "That’s where this cannon part comes in." He indicated the round opening at the front. "These panels just inside the mouth generate spectron-field pulses, basically the same sort of technology we use in the repelatrons. But they don’t cause a repulsion effect; the spectron waves bounce off the surface the machine is aimed at, like a radar beam. The returning waves give a little nudge to the dislodged particles and carry them right into the intake cylinder, where the particles—it winds up as a powder—get compressed into a storage reservoir here at the rear of the platform."

"And it won’t accidentally strip off all that gold?" inquired the young Pakistani.

"Let’s hope not! Like the repelatrons, the impeller-waves can be tuned to affect certain materials and ignore others. That’s the ‘selector’ part."

As Bashalli nodded pertly to indicate that she understood, Sandy pointed out another part of the device which Tom had not yet mentioned. Suspended from a long overhead boom, it was shaped like a funnel and hung a few feet above the front end of the cannon. A jointed hose spiraled back from the narrow neck of the unit, branching out to connect to a number of cylindrical metal tanks. "And what’s this for, Tomonomo?"

"I call that part the moleculetron," Tom answered.

Bud interrupted with, "I haven’t come up with a nickname yet, but I’m workin’ on it."

"What it does," Tom persisted, "is separate and process the gaseous products arising from the treatment. The spectronic beams can be made to reflect back at slightly different angles. It’s like the way a prism separates rays of light into different colors. The heavier particulates go into the cannon, but the lighter free molecules—gases—are conveyed into the moleculetron, which selects-out the various elements and basic compounds for more efficient storage. For safety, we don’t want to leave anything floating in the air."

"Don’t you mean, in the water?" Bud pointed out.

"Nope. We’ll be using the spectrosel inside the hydrodome airspace created by the repelatron."

Bashalli noted the delicately crafted miniature control panel next to the rear of the cannon-cylinder. Studded with tiny levers and dials, it appeared extremely realistic. "It ought to be," commented Tom with pride. "This is as accurate a scale model as Arv and Linda can make, and it’s fully functional."

"This little model actually works?" Bashalli asked in amazement.

"Sure," Tom turned to Bud with a grin. "Like a little hair off the top, pal?"

"Please! Don’t experiment on me, Professor!"

Bashalli held up her leather purse with silver initials. "The purse is new, but these letters already need polishing," she said playfully. "Could your machine remove the tarnish?"

Tom hesitated, a doubtful look on his face. "Well, actually—the spectromarine selector is designed to work on materials with water content. I don’t know if—"

"Aw c’mon, genius boy!" Bud urged teasingly. "The Swift honor is at stake!"

"All right," said the young inventor reluctantly. "I suppose it can’t do any harm."

As Bash held her purse about a foot away from the cannon, Tom aimed the model at the metal initials. Then he flicked on the power, provided by a miniature solar battery, and gently pushed a lever forward with the edge of his fingernail.

"Ohhh!" Bashalli and Sandy shared a delighted gasp as the tarnish seemed to fade away like magic until it had completely disappeared. But their amazement quickly turned to dismay as the initials too began to vanish! Before Tom could fumble his fingers into position on the tiny levers to turn off the machine, even the leather was partly eaten away!

"It’s ruined!" Sandy groaned.

Tom, red-faced, hastily apologized.

"Don’t worry, Thomas," Bashalli said good-naturedly. "It’s an old purse, anyhow."

"You said it was new."

"Now it’s old."

"But what happened?" Sandy asked. Tom explained that he had adjusted the machine to remove tarnish, a sulfide compound. But the selector circuit, by an unexpected feedback action, had also ordered the selector to remove the metal alloy, which contained a sulfurous base.

"There’s sulfur in the leather, too," he added. "So the spectrosel took part of that off!"

"Just a slight slip-up," Bud grinned.

"It’s a problem that could cause plenty of damage," Tom noted ruefully. "I’ll buy you a new purse, Bashalli, and let’s say this one went for the cause of science. At least it showed me a flaw in my machine that needs correcting!"

"I trust you are no longer bored," commented Bashalli.

The next morning Tom returned to work at the plant over his mother’s resigned and half-hearted protests. He made a quick tour of the various departments to check progress on the full-sized version of his new invention. Luckily there was still time to make changes in the spectrosel’s differential-detector unit. Having developed a promising approach, he went to confer with Art Wiltessa, a brilliant young engineer who often oversaw the construction of Tom’s inventions. He had supervised the production of many of Tom’s projects from blueprint to working model.

But before three words had escaped Tom’s mouth, his pocket cellphone bleeped. Tom apologized to Art and answered the call.

"It’s Ames, Tom," said a tense voice. "I’ve received some new info on this Li Ching guy. It looks like you’re in for some real rough sailing!"

"I’ve been in touch with Hal Brenner, the FBI agent you’ve dealt with," Ames responded. Agent Brenner had previously assisted Tom when he and Hank Sterling had been imprisoned during the run-up to Tom’s flight to South America in his Flying Lab. "He was given permission to tell me what they know about Mr. Li. The main source is Interpol, although I think Brenner was hinting at some sources in the CIA and the domestic terrorism office."

"And maybe your cousin Steve?"

Ames chuckled. "Tom, you should get out of inventing and become a detective! At any rate, here’s what I was told, boiled down. Turns out Li is, officially, Comrade-General Li Ching, former head of the technological research division—weapons, in other words—of the Army of the People’s Republic of China. He was suspected of marketing secrets to Taiwan, but fled the country before he could be arrested."

"So he’s a traitor."

"Yes, and worse—he’s thought to be the leader of a sort of international spy-for-hire ring with a specialization in high-tech theft. Brenner describes him as ruthless and murderous."

"We’ve definitely seen that!" Tom declared. "But just how is he involved in this Mob-Kranjovia connection?"

"Brenner’s stumped on that one, and so am I," admitted the security chief. "It’s possible, of course, that some entirely separate group is trading on his name. But there are a half-dozen government offices at work on the problem—not to mention Enterprises’ own security aces!"

"I’m betting you solve it first, Harlan!" commented the young inventor appreciatively. "Thanks a lot for the report."

"Watch your backside, Tom."

"That’s hard to do," Tom joked. "I’ll let Bud watch my backside, and I’ll watch his."

Turning his attention back to Art, Tom described the flaw that had spoiled his demonstration on Bashalli’s purse. "I think I have the answer," he added.

Pulling out pencil and paper, Tom sketched a feedback-control circuit which he had worked out in his mind overnight. Its purpose was to prevent the compounds in the object being cleaned from affecting the selection of elements to be removed.

"Good enough," Art commented. He was a man of few words, but his eyes showed his admiration for his young employer’s technical insight. "And we can add that easily before the unit’s assembled."

"Thanks, Art." Tom thumped him on the back. "I hate to slow up your schedule, but we want all the bugs ironed out before setting up shop in those Atlantis ruins."

Having given work to others, Tom was now somewhat at loose ends. After spending some time making entries in his personal journal, he prowled about his several labs restlessly. As noon approached, he was relieved when his telephone buzzed.

"Hi, sis! What’s up?"

"Oh, just felt like giving a call to my famous big brother," was Sandy’s breezy reply. "I don’t suppose you’ll be taking off for the sunken city this afternoon?"

Tom gave a wry chuckle. "Not a chance. We’ll probably work Saturday, though. Lots to do."

"Don’t try to wiggle out!" his sister warned. "Daddy says you have this afternoon free, and we want you to join Bud and Bashi and I on a pleasure outing. Even if you don’t care about your devoted sister and poor Bashalli—she of the abused purse!—you don’t want to let Bud down, do you?"

Tom groaned humorously. "Well, I suppose if you’ve already got Bud’s okay..."

"Meet us in the parking lot in fifteen minutes."

In eight minutes Tom found the girls leaning glamorously against Bud’s scarlet convertible. Bud gave Tom a rueful look. "When they told me you’d given thumbs-up, pal, I figured I’d better come along to play watchdog."

"Huh?" Tom gave Sandy a look of mock accusation. "You said you’d already got Bud’s okay before you called me!"

"No, Tom, you said I’d already got Bud’s okay," Sandy replied blithely. "Can I be blamed for your jumping to a conclusion?"

Bud struck his forehead with his hand. "Genius boy, we’ve been had!"

"A fine thing to say, Buddo," Sandy pouted. "Is there something wrong with us, Bashi?"

Bashalli’s long dark lashes drooped sadly as she smothered a giggle. "It’s no use, Sandra. I fear we’re just not their type."

"Oh well." Sandy shrugged mischievously. "If they have to work so hard all the time, maybe we better find ourselves other dates."

"You know, there are these nice two boys who work at Wickliffe Laboratories..."

This brought a quick reaction from Bud. "Hey, none of that!" he protested. "Maybe we could manage to break away."

Giving up the game, Tom laughed. "So what’s the plan?"

The plan turned out to be an afternoon at Carnival Park, a large amusement park in the old-fashioned style that had just opened in a little resort town at the tip of Lake Carlopa. For weeks, the girls had been begging Tom and Bud to accompany them there.

"Yippee!" Bud burst out gleefully. "This is wonderful, Sandy! I haven’t been to a carnival in a blue moon!"

As soon as they had parked, the four young people hurried off gaily on foot to the carnival grounds. A din of excitement filled the place. The carnival was ablaze with color, highlighted by striped tents and clusters of toy balloons. Barkers shouted in front of the amusement concessions, while children shrieked and squealed with laughter on the fun rides and the merry-go-round.

"Oh, I’m so excited!" Bashalli confessed. "Sandra, this is the best idea you ever had!"

"Check!" Tom agreed, laughing.

"And you didn’t even have to change your signature blue-striped t-shirt, Thomas," she added with irony, and a twinkle in her eye.

The two couples lunched on dogs, fries, and shakes, to which the voracious Bud Barclay added his favorite, roasted corn on the cob. Everywhere they went, strolling Shoptonians nodded hello, for Shopton’s most celebrated citizen was well known to everyone.

"Hey, let’s show Sandy and Bash what hot shots we are!" Bud proposed as they passed a shooting-gallery booth.

"Okay." Tom grinned. "We’ll make it boys against the girls—losers buy cotton candy all around. But let’s not run up the score on ’em too high!"

The girls selected guns and shot their round first. Bing! Bing! Bing! The travelling ducks went down faster than clay pigeons at a rifle match.

"Wow! Almost good!" Bud gulped. Sandy and Bash smiled innocently but said nothing.

When Tom and Bud’s turn came, they were unable to beat the girls’ high score. The boys looked at each other in deep male chagrin as they lay down their guns.

Tom chuckled wryly. "You don’t suppose this could have been a put-up job too?" he quipped to Bud.

The girls burst out laughing.

"I suppose we mustn’t destroy their fragile egos," cautioned Bashalli. "Tom may be needed to save the world."

"Okay, we’ll ’fess up!" Sandy giggled. "We’ve been taking shooting lessons from Chow!" Chow Winkler, a big and grizzled one-hundred-percent Texan, had recently left on one of his periodic trips back to his home in Texas. He had proven himself skilled at the cowboy arts of ridin’, wranglin’, and shootin’.

The boys vowed to do better at the next concession. This turned out to be a booth where the customers were pitching baseballs at a comical-looking dummy. As Tom left them momentarily to fetch the promised cotton candy, Bud sized up the game. "Three shots for a quarter!" the barker shouted. "Nothin’ to it, folks! Hit the dummy and down he goes! So step right up and win your little lady a prize!"

"Okay. Maybe our luck will turn here." Bud, who had been a fireball hurler on his high school team, grinned in anticipation.

Just then a lady bystander snickered. "Hey, that dummy looks just like you, Longneck!"

Bud stiffened. Could the speaker be referring to Longneck Ebber? Beneath hat and sunglasses, the man standing next to the woman certainly resembled the FBI photo Harlan Ames had shown them!

Bud shot a quick glance at Tom as he walked up with the cotton candy. "Tom, that guy over there—I’m sure it’s Longneck," he whispered to his chum. "If he notices you—"

Tom turned to the two girls, speaking quietly and tensely. "Wait over by the ferris wheel, out of sight. We think we see one of that gang, and he could be armed. We’ll be right back."

The possible Ebber, a tall, cadaverous man with a beaky nose, was already walking away with his companion. Tom and Bud followed them at a distance, hoping to remain unseen in the crowd.

But it seemed the mob leader had the sixth sense of a born criminal. He abruptly stopped and turned. His eyes fell on the young inventor, and his slit of a mouth turned deadly.

"Get outa here!" he grunted at his woman friend, roughly shoving her away. Ebber whirled and took off like a startled jackrabbit, plunging violently into the crowd. Tom and Bud dashed after the suspect almost without thinking.

Ducking and weaving to avoid collisions with the carnival merrymakers, the two boys sprinted through the midway. But the crowds of people made it impossible to keep their quarry in sight. They paused to catch their breaths, ready to give up the chase. Longneck Ebber could have slipped off in any of a dozen directions among the tents and concession stands.

Suddenly Tom hissed, "I see him! He’s at that big building over there, behind the ticket booth!" Ebber was standing in line to enter one of the enclosed rides, evidently trying to get out of sight. Even as the youths began to run, they saw Ebber hand a ticket to an attendant and scramble into a boat-shaped conveyance. Over the mobster’s head was a gaudy sign outlined in flickering bulbs: Spend Ten Minutes in The Tunnel of Love!

They attempted to jump the line, but two stern well-muscled carny men warned them back. "Ticket booth over there, boys!"

Tom and Bud rushed up to the booth. "Two for the Tunnel of Love!" Tom demanded, panting as he fumbled out some coins.

"The times they are a–changin’," said the man in the booth languidly. "First some guy wants to ride all by hisself, then you two boys—"

"Come on!" Bud demanded. "We’re in a hurry!"

"I bet," scowled the man, peeling off two tickets.

In moments Tom and Bud were in their two-seater boat, which ran along on a rail partly covered by a shallow stream of water. They glided slowly forward into the darkness of the building. A number of the little boats, filled with ardent occupants, now lay between them and Ebber.

"Can you see him?" asked Bud.

"Nope. He’s somewhere ahead of that bend up there."

There was nothing to do but wait as the boat inched lazily along among the blacklight-lit monsters and weird clown faces. They came to an open place where they could see across to a further point on the track. Tom elbowed his pal. A boat had just emerged into the violet dimness—empty! "He’s jumped out somewhere!" Tom exclaimed. "He must be trying to get out through a back door!"

"Trying to shake us," Bud gritted. "But we won’t be shook!" He stood in the boat, pulling Tom to his feet. They jumped off onto the painted "shore," their feet crunching down through its foam covering as they sprinted across toward the opening of the dark section that the empty boat had just emerged from.

Then, accompanied by startled screams, a gunshot crackled through the purple shadows!

"Lookit that!" laughed a boy somewhere ahead. "Man, this ride has everything!"

Rising cautiously, the boys made their way forward at a crouch. "Look down there," Tom whispered. "Footprints."

They crossed the stream, using the prow of a passing boat as a stepping stone. "Sorry," Tom muttered to the riders.

"Having a good time?" was Bud’s contribution.

They crept through an archway into another section—and halted with stunned gasps. A lean, longnecked figure was hanging from an overhead beam, arms dangling down limply, so low that the laughing riders had to duck beneath his fingers.

Tom and Bud made a slow approach, jerking back at one point when it seemed an arm had twitched. But it was only the nudge of a head brushing as it passed beneath.

Tom drew close and touched the body.

"Dead?" asked Bud.

Tom nodded. "Bleeding from the back. That shot was meant for Ebber, not us."

Even in the dim luminance they could make out a small square of white against the late Longneck Ebber’s dark shirt. Li Ching’s calling card!

After a long afternoon with the local police, carnival officials, and a pair of sour-faced young ladies, Tom and Bud ended their day of carefree amusement conferring with Harlan Ames and Mr. Swift back at Enterprises.

"No trace of Longneck’s female companion," reported Ames. "Matching Bud’s description to yours, Tom, we think it was the same woman who stopped you out on the road."

"So now this Li Ching character has racked up two victims from the Mayday Mob," Bud noted. "Someone must have been following Ebber."

"And was Ebber following Tom in turn?" asked Damon Swift. "We found a gun—Ebber’s—on the floor near the body. He must have drawn it."

"Nobody could have known that we’d be at Carnival Park," Tom put in thoughtfully. "More likely he was holed up somewhere in town putting together some more dirty work, and decided to take his lady friend out on a date."

"It’s enough to make you give up dating," Bud remarked. "Long as I live, I’ll never go into another Tunnel of Love!"

"Comrade-General Li may be taking out the bad guys for now," stated Ames, "but who knows what he’ll turn to later."

Seeing the look on his father’s face, Tom said gently, "We’ll be safer underwater. When is Lieutenant Fraser supposed to get here?" Lieutenant Brian Fraser was the assigned replacement for Cromwell, who was still hospitalized.

"There’s been a change in plans," Mr. Swift answered. "I received word this afternoon, while you were all off enjoying yourselves. Fraser is on Fearing, where he’ll stay until the expedition is ready to depart."

"I’ll say Monday’s the day, Dad. The spectromarine selector should be ready by then; I think we can load it onto the Sky Queen Sunday afternoon. All three mantacopters are already waiting in their berths on Fearing."

"Your science team gets here tomorrow morning," Ames added. "I’ve checked them all out, and so has the FBI. More than once!"

"It’ll be great to see Ham and George again!" Tom grinned. George Braun and Hamilton Teller were a lively, bantering pair of scientists with a background in oceanography and archaeology and a powerful interest in the Atlantis legend. They had been part of the first seacopter visit to the city of gold.

Ames winked. "I’ll do my level best to keep you boys alive, at least through tomorrow morning."

Bud had the last word. "Could you make it tomorrow evening? I have afternoon plans."

The next day, Friday, brought not doom but a diversion. Anticipating the arrival of the science team by plane, Tom’s wait in his office was interrupted by the office secretary, Munford Trent. "Tom, there’s a Miss Gabardine here to see you."

"Does she have an appointment?"

"She claims not to need one. She says she’s here from the Treasury Department—official business." Trent approached Tom at his desk and spoke softly. "Please don’t make me argue with her any more, Tom. It’d take an atom bomb to pry her out the door!"

Tom chuckled under a sympathetic look. "All right, let’s see what she wants. I’ll keep a finger on the security alert button."

"They’ll need to send a squad."

In a moment a woman marched in, her stride forceful and determined. Tom knew instantly that this woman was unique, in that she lacked a description. In all respects she was as plain as the national average, neither tall nor short, young nor old, stout nor thin. Her hair was a mousy color floating somewhere between brown and blond. Her outfit was gray, dignified, and thoroughly businesslike—and it was clear she meant business!

"Julienne Gabardine," she declared, offering her hand. "I apologize for arriving in this abrupt manner, but this is our method of operations when we conduct an inspection."

Tom was puzzled. "An inspection?"

She seated herself unbidden. "Not in this case, actually. I am here as an Evaluator on behalf of the United States Department of the Treasury. Swift Enterprises, or rather your current exploration project, is my Evaluatee. Her are my credentials. Feel free to contact the Department for verification."

Tom glanced at them politely, knowing that he would pass them along to Harlan Ames. "Well, Julienne—"

"Miss Gabardine, if you please. I prefer to keep this relationship at a professional level. I am unmarried, but I would be grateful if you would inform your employees that I am not available for socializing."

"I’ll pass along the word, Miss Gabardine," responded Tom with a smile. "I’m afraid I’m not clear on the purpose of your visit."

"No, of course you aren’t. I am assigned the responsibility of reporting on, and generally evaluating, your use of the Federal funding granted you for certain well-defined purposes with respect to your proposed activities at the subocean archaeological site."

"I see," nodded the young inventor as his smile faded. "Of course, the government is involved in the project, and has sent us an observer. Really, though, ma’am, nearly all the costs are born by Enterprises."

"I don’t make the rules, Mr. Swift," was the curt reply. "This is required by Federal regulations, which I am prepared to cite if you wish. International agreements are also involved."

"We’ll make your visit as easy as possible, Miss Gabardine. I suppose you’ll need access to our files and records?"

"Eventually."

"Excuse me?"

"Mr. Swift, I am to accompany you on the voyage, to evaluate your project and its expenditures on the basis of firsthand knowledge."

Tom drew back in his chair, astonished. "But—ma’am—this is a complicated scientific operation on the ocean floor! I don’t see how we can be expected to accommodate—"

This woman stood, her attitude politely dismissive. "You might like to have your legal office examine my credentials. My scope of authority is absolutely definite. I won’t interfere with the science, Mr. Swift. As I understand it, you will be providing a surface type of environment at the site, so no special training would seem to be necessary. But my presence is necessary, if your project is to go forward."

Tom boggled but said calmly, "Departure is scheduled for Monday."

Miss Gabardine gave a crisp nod. "I’ve taken a hotel room in Shopton. Here is the number. No doubt it would be best for me to spend Sunday night here, on the premises, so as not to delay you."

"We’ll arrange it." She turned and marched out, and Tom wiped his brow. Good night, wait’ll Dad hears about this! he thought.

The science team, eighteen men and women from various scientific fields and several nations, arrived at Enterprises at the tail end of the busy morning. Tom and Mr. Swift greeted them and had them shown to their comfortable quarters on the grounds of Enterprises.

"Great to see you, you two!" exclaimed Tom warmly as he shook hands with Ham Teller and George Braun. "It’s been too long!"

The two scientists were very different from one another. Red-haired Braun was pudgy and animated, while Teller, tall and balding, was wry and relaxed. His inflection bespoke his Brooklyn upbringing.

"Yaa, well, we’ve been busy, sorting out all that stuff from the Ocean Arrow trip," responded Ham in half-apology. "Brauny here can’t turn over a piece o’ paper without getting himself distracted."

"Sure, Ham, blame the short guy!" retorted George Braun. "As you remember, Tom, I’m the one who’s precise and thorough. Teller lazes around playing computer games when I’m not looking."

Tom laughed. He knew the two were the closest of friends, and topnotch scientific researchers.

Monday arrived. The scientists, Swift technicians, spectromarine selector—and Miss Gabardine—were loaded aboard the Flying Lab. Doc Simpson was also accompanying the mission, to study the physical effects of longterm living beneath the sea.

But the ceiling of the huge underground hangar did not split in two and open. The Sky Queen’s special platform did not lift it up into the morning sunlight. Instead, the clock ticked.

"Where is he?" groaned Bud Barclay. "Are we really sure he flew in last night?"

Tom nodded. "Absolutely, pal. He brought me a rattlesnake sandwich at eleven PM!"

A big, round, frantically waving figure came bounding across the hangar concrete, unheard on the other side of the thick cockpit viewpane.

"That’s our boy," Bud snorted humorously. "That shirt could run all by itself." Chow Winkler’s gaudy color preferences had become the stuff of legends at Swift Enterprises, along with his formidable, if sometimes eccentric, prowess as special executive chef. Since Tom and his father had brought him back from a New Mexico ranch, he had become a favorite at Enterprises, and one of Tom and Bud’s closest friends. It was a rare operation that lacked Chow Winkler’s special touch.

The ex-Texan arrived panting in the control compartment. "Brand my slitherin’ snakes!" he gasped. "Got m’self jet-lagged! I ’as hard asleep when th’ dang alarm went off!"

"Couldn’t leave without you, pard," Tom said affectionately. The older man beamed through his broad leathery face.

Finally gliding vertically above the clouds on its bank of jet lifters, the mighty stratoship made for the sky, heading south toward Fearing Island at supersonic speed, Hank Sterling at the controls while Tom and Bud chatted with their colleagues and friends in the top deck lounge.

"What a beautiful blue sky it is up here," murmured one of the geophysicists, Dr. Emmaline Norliss. "Have you flown the stratosphere before, Jul—mm, Miss Gabardine?"

"Once or twice," replied the Treasury official. "But I tend to look at things from the standpoint of efficiency."

"Oh, upper air travel is very efficient," put in Arv Hanson jokingly. "Gives a person time to think—clears the brain."

"And you leave trouble down below," Bud said. Then he added: "Unless you fall out of the plane, of course."

Tom winced. "Let’s not bring that up, flyboy!" It had happened to Tom!

The Sky Queen flew on to Fearing Island. Ever since the small, barren stretch of sand dunes and scrubgrass off the Georgia coast had been converted into the Swifts’ top-secret rocket-testing facility, it had come under high-security protection. It was circled without pause by midget drone jets, and a radar monitoring system, the patrolscope, was constantly alert to any unauthorized entry.

The Flying Lab circled as it approached, giving a view of Tom’s huge repelatron spaceship, the Challenger, as well as the docking facility where the three mantacopters were berthed.

"How kin you tell ’em apart?" asked Chow.

"Only by looking at the names painted on the hulls," was the reply. "Besides the Deepwing, there’s the Supermanta and the Fathomer—all loaded and ready."

"Wa-aal, ya shoulda let ol’ Chow name ’em, boss," Chow declared. "Got me a whole passel o’ names ready fer use. Good ones, too."

"Hey, Chow, you already got to name my new invention," Tom laughingly reminded his friend. "I was all set to call it a ‘spectron selectrol’—then I remembered my promise."

"Right good thing, too!" Long before, Tom had promised that he would use a name the cook had come up with, spectromarine selector, at the earliest reasonable opportunity.

After clearing with the tower, the team landed on the island airfield and sped by jeep caravan to the submersibles support building next to the docks. A crew was standing by, ready to load the final supplies, and the spectrosel, onto the waiting mantacopters.

"I’ll miss riding in the Sea Hound this time out," Bud remarked, He pointed off into the distance. "Your helicopter-submarine is all slicked up and ready, looks like." Dwarfed by the mantacops, the saucer-shaped seacopter gleamed in the bright Atlantic sun.

Tom nodded. "She’s a great ship. But she’ll be here waiting for us when we get back."

A young, red-haired Navy officer now approached, accompanied by Phil Radnor. "I’m Brian Fraser," he said as he shook hands with Tom. "The real thing!"

"Good to meet you, Lieutenant." Tom noticed that the new man wore the twin gold dolphins of the submarine service. "You’ll be right in your element on this trip."

Fraser grinned pleasantly. "I’m looking forward to it!" He conveyed greetings from Admirals Hopkins and Krevitt.

The team and crew split three ways. Tom decided to make the voyage in the Fathomer along with the cannon—which had now become the official nickname of the spectromarine selector. He was joined by Bud, Chow, George and Ham, Zimby Cox, and, at her own insistence, Julienne Gabardine. The young inventor thought it best not to argue.

"I’ll take the Supermanta," Fraser decided. "Best not to put all the brass in the same hull!"

Tom took his place at the controls, with Bud beside him in the copilot’s seat. He flicked on the atomic reactor control system, shooting steam to the turbines which spun the enclosed horizontal rotors. With a purring hum the mantacopter floated skyward from its docking cradle.

"How high will we be flying, if I might ask?" inquired Miss Gabardine.

Bud answered for Tom. "About eight feet, ma’am. A little higher if our captain feels daring."

The woman frowned slightly. "Please don’t feel obliged to be daring on my account."

As the other two mantas fell into line behind the Fathomer, Tom cut in the forward jet tubes and the super-seacopter went streaking off to the north.

"Hey! Where are we heading?" Bud questioned with a look of surprise. "The North Pole?"

Tom grinned and shook his head. "Just a slight precaution to mislead any spies." He jerked a thumb toward the ceiling. "You never know who may be up there tracking us—even by satellite!"

"Right—maybe even those space friends of yours who sent that rocket," added Ham Teller, referring to the capsule of extraterrestrial plantlife they had recovered during the earlier seacopter mission.

The youthful captain flew northward for almost a hundred miles, then abruptly altered course toward the southeast. The fleet adopted a zigzag course. Far out over the mid-Atlantic, Tom brought the mantacopter down and submerged. But even below the surface, he circled and zigzagged warily for a time, which allowed the crew to watch as the other two craft plunged down behind them, sloshing through the gentle swells in swirls of foam.

"Jest like Columbus," Chow remarked. "Three ships! You coulda called ’em the Nina, Pinta, and th’ Santa Maria. O’ course, we’re headin’ in th’ other direction."

"Any blips?" Tom asked Zimby, who was scanning the sonarscope.

"All clear, skipper!"

Finally convinced they were free of any possible pursuers, Tom laid a course for the sunken city of gold. Hours went by as he and Bud watched the deep-sea fish and other colorful ocean life pass by in the greenish waters outside the Tomaquartz window of the cabin.

"Not quite as fast as your jetmarine," Bud commented, stifling a yawn.

Tom chuckled. "Relax and enjoy the scenery."

Just then Zimby called out. "Tom! I’m picking up a signal on the all-range!"

"You mean a voice transmission?"

"No, just a steady tone. But it’s on the international emergency channel!"

"And what does that mean?" asked Miss Gabardine.

Tom shot her a worried glance. "That means it’s a distress signal. Someone’s in trouble somewhere ahead—and down deep!"

Tom activated his sono-resonance locator device. "Eight miles to starboard, twenty two point four degrees."

"Got a depth reading, skipper?" asked Bud.

"Deep!" said Tom brusquely. He picked up the control panel microphone and commed the other mantas.

"We picked it up too, Tom," responded Hank Sterling in the Deepwing. "What are your orders?"

"We have no choice but to check it out," replied the youth. "It’s possible we’ll have to mount some sort of rescue operation. But frankly—it could also be some sort of trap! Hank, stand-to for ten minutes or so, then follow. You too, Supermanta."

"Aye-aye," signaled Slim Davis.

The Fathomer now put about and Tom poured on the steam. The sea floor sped by under the bright glow of the electronic aqualamp. "Volcanic terrain," noted George Braun quietly. "Rippled, jumbled, and cracked."

The broad terrain of Chow’s forehead creased. "I’m feelin’ a mite thet way myself."

"She’s right ahead, Tom," Zimby reported. "But down below—must be sitting right on the bottom."

"Then we’ll go down to meet her," declared Tom tensely. Moments later, a gentle thud announced that they had settled on the sea floor.

"Look!" Bud gave a startled gasp and pointed out the cabin window.

Dead ahead, in the full glare of the seacopter’ s beam, lay a strange submarine!

"What in the world kind of ship is that?" muttered Ham.

The submersible looked to be about sixty feet from prow to stern and consisted of three flat-sided hulls in parallel. At the rear of each was a spherical module which Tom sized-up as a deepwater diving vessel of some kind, probably detachable. Each hull, as well as the diving spheres, bore a small round porthole streaming with light. The mysterious craft remained motionless, betraying no sign of hostile intent, or life of any kind. Its crew, if any, seemed unaware of the Fathomer’s presence and gave no response when Tom called the submarine over the sonophone.

"No answer on any frequency," he stated. "Just the emergency signal."

"What do you make of it, skipper?" Bud asked with a puzzled scowl.

Tom was equally baffled. "You’ve got me, Bud. I can’t even guess its nationality." He paused thoughtfully. "And yet..." From the manta’s onboard computer he brought up a searchable listing from Jane’s and paged through it. But he found no submarines pictured with lines like those of the unknown craft.

"Must be some new type that’s been kept top secret," Tom muttered. "Especially to be operating at this depth!"

"What do you intend to do?" inquired Miss Gabardine. Her tone suggested reservations.

"I intend to use some of that ‘funding’ of ours to save lives." He shot Bud a quizzical glance. "Are you game to pay ’em a visit?"

"In Fat Man suits?" Bud grinned. "Sure, why not? Boy, will they be surprised to see us at their front door!"

Tom and Bud each squirmed into a suit and clamped shut the top-to-bottom access hatches. Moments later, the queer-looking steel monsters squeezed their way out of the contoured hull apertures. Those aboard watched tensely through the cabin windows as Tom and Bud waddled forward through the undersea murk. Each suit carried its own set of spotlights. At this depth the Fat Men were under extreme pressure and bone-chilling temperature. But inside, Tom and Bud were perfectly comfortable as they made their way along, their legs extending downward into the suits’ motor-assisted limbs.

Reaching the mystery submarine, Tom manipulated his Fat Man’s arm controls to rap on the hull. Repeated knocks brought no response.

"Maybe there’s no one aboard," Bud remarked over his suit’s sonophone.

"Just what I’m thinking." Tom’s face, seen through his Tomaquartz view dome, bore a puzzled frown. "It may even be a derelict."

"With an automatic signaler that’s on the blink. So what do we do now?"

"Let’s jet over to the other side."

They used their small suit jets to hop over the hulls. Landing gently, Bud suddenly called out: "Look—a name!"

"Good night, no wonder she seemed familiar!" Tom exclaimed. "It’s the Hydra-Gaea, Professor Centas’s research deep-diver!"

"Who’s he?"

"In a few minutes, pal, he’ll introduce himself."

"Hope so." But Bud was secretly fearful that the submarine’s occupants might be found dead.

They looked through the forward portholes but saw no signs of a crew. "At least she doesn’t seem to be flooded," Tom noted. "Let’s check out those spheres at the other end."

As he approached the porthole in one of the spheres, Bud cried out, startled. A dark silhouette had moved into view!

"It’s Centas himself!" exclaimed Tom. "And someone else, too. But their communications must be out."

Communicating by gesture, Tom indicated that rescue was immanent. He contacted the Supermanta, which now had arrived and was hovering some distance away, and gave detailed instructions to Hank Sterling and Arv Hanson. The mantacopter drew near and settled down onto the bottom, one of its side freight hatches almost touching the occupied sphere. Inside the big airlock, the two expert technicians had bolted down one of the powerful repelatrons the sub was freighting to the city site.

"Hank says they’re all set," sonophoned Brian Fraser. "Shall I tell ’em to switch on?"

"Right—radius fifty."

In a moment the occupants of the Hydra-Gaea were witness to a sight few on Earth had seen, the birth of an airspace bubble at the bottom of the sea. The bubble seemed to grow right out of the manta’s hull, partially penetrating the ground as it expanded. In moments it encompassed the entire stern of the Hydra-Gaea with its three metal spheres.

The young inventor now gestured for the occupants to emerge into the airspace.

"Man, I just hope they trust us!" Bud remarked. "It’s a little offputting, climbing out of a sub at the bottom of the ocean!"

"Professor Centas knows all about the repelatron and hydrodome setup, Bud."

A round hatch slowly opened. The man Tom had recognized crawled out into the airspace, followed by the other occupant, who was unknown to Tom. Lugging along a large metal case, Centas closed the hatch behind him. The two were directed to the Supermanta’s wide airlock hatch, which had swung upward, gullwing-fashion. After it was shut and sealed again Tom ordered the repelatron powered-down, and he and Bud returned to the Fathomer.

"Fantastic!" exulted George Braun.

"Aw, calm down, George," snorted Ham Teller. "It’s all in a day’s woik for this guy." But he clapped Tom and Bud on the back, and Zimby and Chow added their congratulations.

Julienne Gabardine held back, making no comment. But the boys could see her jotting some notes in the small notebook she carried.

Tom sonophoned the Supermanta and confirmed that there was no one else aboard the disabled craft. "How are they? Do they need medical attention?"

"Doc Simpson says they need attention, all right, but they’re not in critical shape," Hank reported. "He thinks they can be treated at the sub-city."

"Then it seems there would be no need to turn back, I take it," Miss Gabardine commented.

Tom glanced at her, irritated. "Not at the moment, ma’am. We’ll proceed with the mission and give our medical man a chance to evaluate them."

"And what about their submarine?"

"The Hydra-Gaea is anchored in place. It’ll stay put for now. It’s not our business to salvage it—it’s not an American ship, and belongs to a private research foundation that Professor Centas heads."

"They should jest be glad t’be alive," Chow added.

"I’m sure they are, Chow," Bud said. "If not, we’ll throw ’em back."

The fleet now resumed the voyage, ascending a ways toward the surface to avoid the jagged upthrusts of the sea floor. They skirted the Madeiras and headed northward until they sighted the Horseshoe Seamounts that concealed their destination. They were soon directly over the city of gold, two miles down. Tom shoved the control wheel forward and the Fathomer plunged toward the ocean bottom.

The waters darkened and gradually became pitch black. Tom switched on the powerful undersea searchlights. Presently the rugged crags surrounding the slotlike entry channel lay dead ahead. "Here we go," he sonophoned. "Use sonar guidance to keep to the middle, away from the channel walls. There should be plenty of room."

They plunged into the darkness beyond the yielding curtain of vegetation, Tom’s mantacopter in the lead. They angled downward moment by moment, involuntarily listening for the scrape of hull against rock.

Tom checked over the automatic instrument readouts. "No problems with the guidance system. It should be just—"

"Tom! Hard to port!" It was Bud’s frantic warning!

Acting almost automatically, Tom flicked over to manual control and twisted the wheel. What had caught Bud’s attention was now visible to all of them.

"B-brand my seaweed cutlets!" gasped Chow. "A sea serpent!"

A weird, luminescent sea creature was darting toward them!

"I’ll try to scare him off," Tom muttered. "He might foul the rotors if he gets himself sucked in." The young inventor swiveled one set of the gimballed jet tubes, aiming them forward, and shot a plume of white, steamy froth toward the creature. It paused and drew back for a moment, almost like a cobra poised to strike. But it seemed only annoyed, not fearful. Its black protruberant eyes, extended forward at the ends of waving stalks, glared lidlessly at the invader. Powerful jaws gaped open, revealing an armory of spiky teeth that curved like scythes.

"It’s starting to coil!" warned Zimby Cox.

The serpent’s intent became clear. Like a huge boa constrictor, it was preparing to wrap itself about one corner of the Fathomer’s kiteshaped hull, dangerously close to the portside rotor well and its whirring blades. The result could be catastrophic!

It charged—but Tom Swift charged first! With a burst of jet steam he rammed the curving prow of the mantacopter right into the nose of their attacker! For a moment the veined gell of the beast was pressed against the viewpane as it thrashed about wildly, stirring up clouds of murky froth mixed with streamers of luminous blue fluid. The Fathomer rocked and trembled.

Then suddenly the creature darted away. The aqualamp beam showed it plunging into a narrow crack in the looming wall of the channel.

"Let’s hope it stays in there till the mantas have passed!" Bud gasped.

"We may have gotten in the way of its daily commute home," was Ham Teller’s remark. "Oh, and Chow?"

"Huh?"

"Whatever you’re thinking, forget!"

Chow’s fondness for experimental cooking was almost as notorious as his shirts.

Moments later, the Fathomer was plunging back down toward the enclosed canyon. As the channel opened wide, Tom brought the giant seacopter to rest on a slight rise among the undersea peaks that afforded a panoramic view. The two trailing mantas were hovering nearby, their lights illumining the pillared ruins of the encrusted golden city.

"In-co-redible!" Ham Teller gasped in Brooklynese, peering out in amazement at the scene.

"Calm down, Ham," remonstrated George Braun. "We’ve been here before, remember?"

"What’s the procedure now, Tom?" Zimby asked. He noticed that Miss Gabardine was listening intently.

"Bud and I will go over to the Supermanta and start the primary repelatron working, since it’s already been moved to the airlock, while you and the Deepwing get into position," Tom explained. "Take charge while I’m gone, Zim. And keep a sharp alert for enemy craft coming down the chute!"

The young inventor and Bud quickly climbed into Fat Man suits and propelled themselves toward the nearby cargo carrier. The boys entered through one of the freight airlocks and crawled out of their steel eggs. Greeting the excited crew, Tom gave instructions.

"We’ll need two men to help us set up the air machine, fellows. In the meantime, please finish prepping the big repelatron for the anchoring maneuver." He nodded at Hank and Arv, the technical experts aboard.

"Right, skipper!" Arv responded.

The young oceannaut took a moment to visit the two rescued crewmen in sickbay, who were resting in cots under the watchful eye of Doc Simpson.

"We surely owe our lives to you and your companions," murmured Professor Belam Centas, his accent showing his Spanish-French origins. He was a wiry man of late middle age, his hair thick and iron-gray, his skin very pale. "My dear Hydra-Gaea decided to betray me."

"We can discuss that later, sir, after you’ve rested."

The researcher nodded weakly. "Your Navy man has spoken to us. It seems it would be easier in many ways if we remained with your expedition until the completion of your remarkable project, which he described to us. A matter of secrecy, we were told. All very exciting, and we have no objection, if you will kindly inform the Foundation, in France, of these matters."

Tom promised to do so and turned to the other man, stocky and black-haired. He spoke with difficulty, evidently little tutored in the English language. "I am Mordo, his assistant and student. I must thank you also, Mr. Swift."

Tom, Bud, and their two assistants, Nina Kimberley and Mel Flagler, all clad in Fat Man suits, exited the mantacopter. They proceeded to set up the osmotic air conditioner machinery on the outskirts of the city. This device would draw dissolved oxygen and nitrogen from the sea water to provide an atmosphere for the air bubble.

When they returned to the Supermanta, the repelatron was standing ready for action in the open airlock. It consisted of a large metal sphere, some five feet in diameter, mounted on a thick platform, together with a console and electronic control panel. The sphere functioned as the radiator-antenna which beamed out repulsion rays in all directions. During the mission it would be connected by thick cables to the mantacopter’s atomic power plant.

"Okay, folks, let’s slide it out to the anchor point," Tom directed. Reaching a spot on the rise, the repelatron was set down and long anchor-screws drilled themselves into the solid rock beneath.

Tom adjusted several tuning knobs, then gripped the repelatron control lever, ready to switch on power.

"Ay-Oke, genius boy?" commed Bud.

"Here we go!"

Tom threw the master control switch, and a balloon of air began to form in the water around the radiator sphere. After checking the readouts, the mission leader increased the power, manipulating the dials with the fingers of the Fat Man’s robotic arms.

"Thar she blows!" Bud grinned with excitement as the giant bubble of air expanded with a leap in all directions. Its inner air, temporarily at very low pressure, was being released from tanks in the repelatron’s platform.

Steadily the repelling waves forced back the sea water on all sides. The bubble grew bigger and bigger until it took in the Supermanta stem to stern and continued outward and upward to the canyon wall. As the other craft maneuvered away, the airspace swelled still more, becoming a domelike hemisphere as its lower reaches effortlessly penetrated the ground. When the bubble reached the point where the osmotic air conditioner had been set up, Tom sent a remote-control signal from his Fat Man. Instantly the machine thrummed into action, spreading a pleasant, less humid atmosphere through the bubble. A green signal light flashed as normal air pressure was reached.

Tom opened his hatch and climbed out of the Fat Man and took a deep breath. "We’re in business, fellows!" he announced, grinning. The air bubble now extended to a radius of one thousand feet, its limit. For the first time in millennia, blocks of the city of gold waited in eerie silence in the open air!

"Okay if the rest of us get out too?" asked Nina through her suit’s external speaker.

"I’m afraid not," was the apologetic response. "I just got out to give the air the old lung test. We need to help set up the other repelatrons."

Even the large-size repelatron was not powerful enough to establish an airspace over the entire site, which was much larger than Enterprises’ helium-extraction encampment. Tom planned to set up two further repelatrons. The hydrodome-bubbles produced would slightly overlap. Based on the mapping survey, they would cover about twenty percent of the sunken city, enough for this initial exploration.

Walking straight through the surface of the bubble with no resistance, the four Fat Men, joined by Arv and Hank, jetted over to the Deepwing, resting a ways along the periphery of the site. They set up the Deepwing’s freighted repelatron, then proceeded on further to the Fathomer. Within the hour, all three repelatrons were up and running, the resulting airspaces enclosed in domes of fine, invisible filaments. Necessary to stabilize the airspaces, the filament barriers flowed effortlessly around people or vehicles.

Crewmembers poured out of all three submersibles, and a sound of muffled cheering drifted across the ancient ruins. As the aqualamps were ineffective inside the airspaces, a bank of Swift Searchlights was set up at each mantacopter location, bathing the scene in daylike radiance reflecting back from the inner surfaces of the hydrodomes.

"Welcome to—er, welcome to what?" Bud interrupted his high-spirited cheer at midpoint. "What do we call this burg, anyway? Greater Downtown Atlantis?"

"Tlaan," stated George with a sly glance at his friend.

"I’m tellin’ you, Tulayon!" thundered Ham joshingly.

"Well, these ruins aren’t the whole sunken island, just a city or town," Tom pointed out with a peacemaking grin. "Let’s call the site Aurum City—‘aurum’ means gold."

Satisfied, Bud cheered: "Welcome to Aurum City!"

The pillared temples and once-magnificent buildings made a breath-taking sight, even though they were now encrusted with barnacles and other sea growths, and mostly shattered to rubble. But a few structures still stood proudly here and there.

A thrill of awe swept over Tom. "Just think, Bud," he murmured, "we’re the first humans to set foot in this city in thousands of years!"

"Gives me goose bumps!" Bud admitted. "But skipper—do you hear something? Tell me it’s just my juvenile imagination, not skeletons climbing out of bed!"

The air seemed full of faint, dull sounds, like whispers and distant mutterings, punctuated by an occasional muffled shout. Tom looked puzzled for a moment, then broke into a grin. "We should’ve expected it, pal—with no water around, everything is less buoyant. Aurum City is just settling in bit by bit, that’s all."

"I can understand. After a few thousand years, you’ve got to stretch a little!"

Excited and fascinated, Tom and Bud left the vicinity of the Fathomer, passing from the relatively bare landing area into grounds strewn with drying ruins and bits of the sea-bottom environment that the retreating waters had left behind. Eyes wide with awe the two boys strolled up one of the ancient streets, now rank with slime, ocean vegetation, and rippled hillocks of sand and loose rock. Stately columns lined the avenue on either side, the encrusted ghosts of ancient ambition.

"I wonder what that was," Bud remarked as they stumbled and crunched along. He pointed toward a once-splendid building, approached by wide stone steps leading up from the street. "City hall, maybe?"

Tom eyed the structure with keen interest. "Looks as though it might have been a palace," he commented. "Or maybe the main city temple."

As the boys turned off the avenue for a closer look, neither n