"Got you, chum," said Bud. "But watch the curve at the cloverleaf."

Tom made the turn neatly, but the tires of the car that seemed to be tailing them turned with reckless squeals.

Swinging off the ramp, Tom took a short cut to the plant. When the other car did the same thing, there was no longer any doubt in Tom's mind that its driver was purposely following them.

With a final burst of speed he shot toward the rear entrance to the plant. The truck's special beamer activated the gate's electronic eye, and as the barrier opened just ahead of them, the vehicle raced through. The solid gate slammed shut instantly. They heard the screech of tires as the car behind turned abruptly and raced off.

"Thank goodness!" said Phyl. "Here's hoping I never have to ride with Herbert again!"

A SUSPICIOUS OFFER 71.

The tension over, everyone laughed. Tom drove the truck directly to the modelmaking division and the young people alighted.

"As soon as we put Herbert to bed," Bud remarked, "we'll go to the party."

The evening's gay festivities helped Tom to forget the strange chase to the plant. But later that night, recalling the incident, he began to think about the advisability of having not one but two giant robots. Then if anything happened to the one now nearly complete, he would have another to take its place. The following morning he started to work on a second giant robot. This one would run on a different frequency as a double precaution. As soon as work on it was well under way, the young inventor turned his attention to the problem of constructing a new relo-trol. During the following two days he discarded one idea after another. Hard at work in his laboratory, Tom became so absorbed that eating and sleeping were almost forgotten.

Chow was worried. "That young genius sure burns himself up like a roarin'

prairie fire," he said to himself, gazing fondly at the youth who sat at a drawing board, a plastic-hooded shade over his eyes. "Brand my mashed mongoose fritters, I jest got to make him eat. . . . Tom," he said aloud.

Tom looked up from his workbench. "I wonder if a high-frequency band-pa.s.s filter would work?" he was thinking aloud.

Chow sighed. "You ain't payin' a coyote's-sized 72 .

attention to me," he complained. The cook scratched at the stubble of his beard and squinted into the glare of the table lamp. "What you tryin' to do, Tom?"

A voice from the doorway answered. It was Bud Barclay with a cup of hot chocolate from the cafeteria.

"It's simple, Chow. Our master electrician here is perfecting a method to stifle random noise."

"Meanin" me?" Chow looked downcast.

"No, Chow," Bud replied, grinning. Trying to imitate Tom's method of explanation, he said, "These are electrical noises built up by cascades of amplifiers used in making a.n.a.logues of the robot's work problems. They disturb the signals. Then when radiation is added-"

"Hey! I think I've hit it!" Tom announced. "The next relotrol will be operated by frequency modulation, just like FM radios. The signals will have nothing in common with radiation and the robot won't be confused."

"Swell!" said Bud. "Now maybe you'll tell Chow we both need something substantial to eat-even mongoose fritters."

"What!" cried the cook in disbelief. "Well, I'll rustle up some Texas grub p.r.o.nto."

Just then the telephone rang. Chow picked it up.

"Tom," he said, after listening for a moment, "Radnor says he's got some important news for you!"

CHAPTER 9.

TELLTALE X-RAY.

"h.e.l.lO, Rad. What's the big news?" Tom asked.

The head of security police spoke rapidly. "We have the leak traced down to one trickle, Tom. Ames and the staff really worked overtime on this one. They went back through miles of microfilm records, first of Enterprises and then all the way into the earliest employment files of the old Swift Construction Company."

"And you dug up something vital?" Tom asked eagerly.

"Nothing from the records," Radnor replied. "But we did learn that a worker in the division where the robot skeletons are fused vanished from town yesterday without any explanation. We're checking on buddies he might have had at the Enterprises plant and also trying to trace his movements."

"Anything I can do to help?" Tom asked.

73.

74 .

"Not yet," Radnor answered. "But we'll let you know. And we'll keep you informed of our progress."

He hung up and Tom relayed the message to Bud. "It looks bad," Bud remarked. "No telling what secrets have gone to your enemies."

Tom was as much disturbed at the thought of disloyalty on the part of an employee as he was by the fact that some of his inventions were being given to outsiders before he could patent them. Not of a suspicious nature, Tom liked to feel that after a new worker had once been screened he could be trusted implicitly.

It was late evening before Tom was able to shake off his depressed mood.

He, Bud, Phyl, and Sandy were in the Swift living room. They had just finished talking about the latest hit records when Sandy said: "Tom, Phyl and I have a wonderful idea-"

"No more robot entertainments!" Tom protested, laughing.

"This is something very different. You're going out to the new atomic energy plant soon. We thought-"

Sandy stopped speaking because the house alarm had suddenly started buzzing. This meant that the protective magnetic field surrounding the Swift home had been activated by the arrival of an unexpected visitor.

Tom leaped from his chair and dashed to the front door. Bud followed. Both glanced at a dial which TELLTALE X-RAY 75.

registered in degrees the amount of metal on visitors, enabling the Swifts to detect any concealed weapons.

"He hasn't much on him," Tom whispered as the bell rang. "About enough to account for keys, watch, and dental work."

Tom opened the door. A short, rather squat man stood in the outer vestibule.

His hair, though dark, was streaked with gray and his complexion was ruddy.

"Tom Swift Jr.?"

"Yes," replied Tom questioningly. "And this is my friend Bud Barclay. Will you come in?"

The man stepped into the hall. "My name's Shanzer," he began. "I'm an engineer with the Tru-type Safe Company."

"Offhand, I can't remember ever hearing of your firm, Mr. Shanzer."

"We are rather new in the field," the caller said. "But Trutype knows you. We understand from one of our men who attended a performance here that your company is building some rather impressive robots. We want to commission you to devise one especially for us."

Tom studied the man carefully. Something about him seemed vaguely familiar. Yet Tom could not remember encountering him before. His name? No, he had never heard of anyone named Shanzer. Had he seen a picture of him, perhaps?

Like a flash a scene came to Tom of Ames, in the Swifts' office, uncurling a photograph between his 76 .

thumb and forefinger. Pins Zoltan! Could this be the bank robber?

Tom offered Shanzer a chair, all the while studying the man. His height seemed to fit Pin's description. True, the hair color was different. Pins was supposed to be a blond, but he could have dyed his hair.

Tom had to be certain. Somehow he must let Bud know of his suspicions and then prove them, one way or another. Tom decided to use the baseball code the boys had devised some time ago to warn each other of impending danger.

"It seems to me that a robot might fit nicely into a business like yours," Tom said. "I could design one that would not only lift heavy safes weighing many tons, but at the same time would be equipped with a set of thin metal grippers with tips more sensitive than those on human fingers. In an emergency it could feel the tumblers and open a safe where the combination had been lost."

Shanzer beamed. "Just what we want," he said.

"Yes, we'd like to play ball with you, Mr. Shanzer," Tom continued.

Bud stiffened alertly at the code signal. He shot a glance at Tom and received a verifying nod. The signals were on!

"Suppose the three of us go over to my lab," Tom said, "and take a look at the various kinds now being developed. In that way, Mr. Shanzer, you could TELLTALE X-RAY 77.

choose exactly those features you want combined in your robot."

Shanzer agreed, then looked inquiringly at Bud. Tom quickly explained that Bud worked with him on the robot project.

Bud in turn gave his friend a puzzled look. If he were suspicious of the visitor, why was he inviting him to the plant? But Tom seemed to know what he was doing.

After their arrival at the laboratory building, it soon became obvious to Bud that Tom was not giving away any secrets. He led them through only nonsecurity areas. As they entered a more specialized section, Bud realized that Tom was steering the unsuspecting visitor toward the small but powerful X-ray machine which Tom had built to help him in his research, and which was always kept loaded with photographic plates.

Bud, on the pretext of illuminating the robot laboratory, went ahead and un.o.btrusively switched on the apparatus.

"While Bud is lighting up the shop, perhaps you'd be interested in this map showing our layout here," Tom suggested to the suspect, who had now been maneuvered to a position in front of the X-ray machine.

Actually the map contained nothing of vital importance, but while Shanzer looked at it, Tom explained a few minor and well-known functions of 78 .

the a.s.sembly-line technique used at the plant. At the same time, several different exposures were being taken of Shanzer.

Tom and Shanzer continued their walk down the corridor. Bud waited to remove and examine the X-ray photographs which had been automatically developed by the machine, and then hastened to rejoin them at the corner.

"Well, Mr. Shanzer," he said, "what do you think of this place? Personally, I feel that when the Swifts built it they were just about batting a thousand."

The code phrase for guilty!

CHAPTER 10.

DEAD-END TRAIL.

TOM UNDERSTOOD the signal perfectly. It meant that Bud had detected something in the X-rays that made him suspect the visitor. Was it surgical pins in his spine?

Before proceeding further, Tom determined to get a look at the X-rays. As they walked on, Bud slipped one of the X-ray photographs into his hand.

Dropping behind, Tom held it up to a light. There was no doubt about it. The man they were escorting was Pins Zoltan!

"He'll probably make a violent denial when I accuse him," Tom thought. "And I can't fight him with that infirmity of his. I'll let the police handle him."

Continuing down the corridor, Tom maneuvered his visitor and Bud toward a hall that ended at a locked supply room, then Tom pressed a b.u.t.ton on

79.

80 .

a nearby panel. A fire door dropped with a bang behind them, sealing off the corridor and isolating the three of them from the rest of the building.

"What's happening?" demanded Zoltan, turning around. "Where did that panel come from?"

Zoltan backed toward the fire door Though tense, Bud gave a forced laugh. "Tom, somebody dropped the ball after the third strike!"

"What ball?" the visitor yelled. "What's the matter with you guys? Are you talking in riddles?"

"From the looks of things," Tom remarked calmly, "it seems the runner was caught off base."

"Caught? What?"

The boys sprang into action. Tom went toward Zoltan as Bud grabbed for a wall telephone. The man backed toward the fire door.

DEAD-END TRAIL 81.