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The cubby in which Robert Dyne spent many of his routine business hours was perched like an eagle’s nest high over the great main apartment of the Dyne Robot Factory. A vertical lift-shaft ran up to it from the lower floor level; and there was access to the cubby from the roof also—a slanting inclined stairway across the fifty-foot upper space to a swinging roof-door giving onto the upper landing-stage where freight-aëros shipped the Dyne Robots to their far-flung destinations throughout Anglo-America.

But Robert Dyne was not in his cubby this June afternoon of 2033. He was on the lower floor, busy and harassed. From the cubby his towering figure with its shock of gray-white hair could be seen as he moved among his human workmen or stood scrutinizing with chilled professional eye the clanking metal robots fashioned in grotesque human form. A hundred or more robots were aiding the scores of human mechanics. Moving belts carried the factory product about the room from one group to another. The place was a clanking, clattering hive of activity.

Gruesome necromancy to one not used to the sight of it, this swift fashioning in metal of a thing so nearly human! A single metal part—a metal torso lying inert on the belt at the start of the two-hour journey around the building. A head bolted into position. An arm added here; a leg a little farther on. A weird metal man, swiftly reversing nature, so that the body became progressively not more deformed but less, until at the end it was made whole and laid inert in the row of externally finished products, waiting to be vitalized—to have its electronic energizers installed, the vastly intricate machinery of its internals connected, so that at last it was almost a human, labeled and tagged with the Dyne imprint and guarantee. And worth variously from ten-hundred- to ten-thousand-dollar-standards.

The testing-ground to the north of the large factory structure held always a hundred or more of the newly vitalized robots, with a group of human mechanicians carefully gauging their reflexes, putting them to every test for which they were guaranteed as products of Dyne manufacture. The radio-controls held by the men seated at small tables along the edge of the testing-ground snapped and hissed with orders. The huge clanking mechanical things slowly responded. And when the remote controls were lifted, still the metal men obeyed a word—or gesture. Or again, they even did their designated tasks unguided. Metal things, which, as the world-wide Dyne advertisements claimed, were in effect human, all but the soul!

This Dyne factory, largest of its kind in the world—located in the northern suburbs of Great New York—specialized in domestic servants. A million were giving satisfactory service throughout Anglo-America—everywhere that English, to which the reflexes were attuned, was spoken. Satisfactory service—until a month before this June day.

The harassed factory-owner strode about the roaring, clanking scene. He went outside; his tall figure, in the black-and-white shirt edged with white, stood motionless as he watched these metal things which his genius had created. Nothing wrong here.

Then he went to the smaller enclosure where the final testing was in progress. The testing for criminality! The small, grave-faced group of human workmen tensed as they saw their chief arrive. One by one the robots were turned loose into the stage-setting of a room which simulated conditions of their coming existence. Every manner of temptation was skillfully offered them, and their reactions checked and tabulated. Nothing wrong here. One by one they were tagged with the final Dyne imprint, and passed back into the stock-room, where the order-checkers would select them in groups to be shipped away.

Nothing wrong? To Robert Dyne it seemed incredible that another day could pass without his locating the source of the trouble. For a month now, his products had not been giving satisfactory service. Dyne robots were committing crimes! Petty crimes mostly—thievery, truancy. But a week ago there had been a case of arson, proved to have been committed by a Dyne robot which for two years had given good service in the home of a San Francisco official. Abruptly the robot had gone awry and had burned valuable property. It was adequately insured, but that did not alter the facts.

The Dyne robots were a menace. Sales began falling off. The Federal Government now had taken notice of the condition. Dyne had a month to correct the trouble, or his factory would be closed. Ruin!

And now by the fading light of the setting sun, he stood watching.

“Seem to act all right,” one of the workmen said. “Chief—”

“No shipments tonight,” Dyne suddenly exploded. “I can’t devitalize all the millions in use! I would if I could—but what I’ve sold isn’t mine. No more from this factory—today or any other day—”

“But Chief—” Joc Vaine, general manager of the industry, put his hand on Dyne’s arm. “See here—you can’t do that. It’s chaos for all our dependent markets. Business ruin for them.”

He was a small man, this Joc Vaine, with a thin, narrow face and keen eyes, and an excitable manner.

“Can’t do it, Chief! I tell you we’ve got to find the trouble, but ship as usual. Chaos—and throw fifty thousand dependents out of work if we stop shipments! You can’t—”

“But I can, because I have.” Dyne towered over the small subordinate. “Suppose a murder comes, Vaine! This fellow here, for instance—” He swung on a metal giant. “Suppose this fellow some day develops the reaction to kill some one?”

Like the ancient monster of Frankenstein, conceived in the fancy of a writer back when robots were a scientific impossibility! Frankenstein’s monster had murdered his master.

Robert Dyne shuddered.

“I tell you, Vaine—no more shipments. We’ve ceased business until this trouble is found.”

Their voices went on. Not only theirs, but everywhere about the factory, human voices were murmuring of the disaster. And up in Dyne’s glassite cubby, where all the interior of the great workshop was visible, the same problem was under discussion. John Dyne, the billionaire’s son, sat at his father’s desk. The girl beside him—slim in her black and white vertically striped trousers and wide flowing silk shirt—sat with anxious, tense face, listening to him. The peak of her black hair grew fashionably low at the center of her forehead. It was short, unruly, curly hair; its curls occasionally fell toward her eyes, so that she tossed them back with a swift birdlike gesture of her head.

Behind her and John stood the mechanical family robot—a seven-foot figure of gray alumite. It stood inert, a monstrous metal statue, travesty of a man. The oval face was ridged and hewn into an expression benign and trusting—frozen there, never-changing. The round lens-eyes were deep-set, glowing with interior light as it stared unblinking. Its label was “Mekko.” It was the highest type of the Dyne robots, and most costly.

John and the girl Aural did not heed it. He was saying vehemently:

“The police searchers should have been brought into this sooner. I know cursed well there’s some human criminal back of all this. Aural, listen! Somebody who wants to harm us—”

“Not so loud,” the girl cautioned. They stared down through the glassite walls of the cubby. And as though he had been listening with a microphone detector, a man suddenly appeared from down near the foot of the lift-shaft. He moved away, out onto the crowded, busy floor.

“Georg Yates!” Aural gasped.

Yates was the chief mechanic in Robert Dyne’s personal employ—a stalwart, black-haired fellow about John’s age.

“Aural, that cheat was spying on us.”

The towering figure of Robert Dyne appeared on the lower floor. He encountered Georg Yates. From the overhead cubby the little group peered down. Yates was violently protesting at Dyne’s accusations.

But the voices were only partially audible. John said:

“Mekko—you listen.”

The robot’s listening ears came out like distended cups. The tiny diaphragms within them visibly glowed. Microphonic ears, mechanically bringing up the soundwaves into complete audibility. This mechanism, labeled Mekko and priced at ten-thousand-dollar-standards, could do many things impossible to a human. . . . From the robot’s mouth came the magnified sounds from the lower floor. The elder Dyne was calling Yates dishonest, and was discharging him. The altercation was over in a moment. Joc Vaine stood in the group. The little superintendent seemed once to intercede, but Dyne silenced him with a thundering voice. Then Yates walked away with a parting angry shout:

“You have no proof. You’re a liar.”

He disappeared, shoving his way through the awed and silent onlookers. . . . Aural said suddenly: “Hear the limp in Sleek’s motor. He’s landing on the roof-stage.”

John Dyne and Aural were waiting here for Sleek Adam. He had been a youthful friend of John’s, they had cubbied together in the Government educational training-camps. When the criminal tendencies of the Dyne robots became a real menace, John had insisted that his father call in the Government police. But nevertheless John had little confidence in the routine police search-squads. They were working on the case now. A dozen men were very likely invisibly here in the factory. But John had more confidence in himself and in Sleek. Young Adam was now in the under-cover Federal service. Nearly all his activity concerned international crimes. At John’s request, Sleek’s superiors had released him to work on the Dyne affair.

John felt Aural’s hand on his arm. He was betrothed to this Aural Granet; the Government eugenic inspection was passed; they were to be married in a month. . . . Aural said tensely:

“Before he comes, John—something I want to tell you. I had a hint—something mysterious from Janna—”

“That girl governess to Joc Vaine’s children? About this robot trouble?”

“Oh, I don’t know!” Aural’s voice was suddenly agitated. “I just thought of it. She said yesterday—just a chance remark—just what one girl would say to another when she’s frightened—and I just realized, Georg Yates made love to Janna once, and she refused him. He threatened her, she once told me. And I—but of course it’s nothing—”

Irritating, this feminine method of indirectness!

“Say what you mean,” John interrupted, rather impatiently.

But what Janna Frane had said to Aural was not revealed. The roof door overhead burst aside, and Sleek Adam came down the incline. He was a small wiry fellow in his early twenties.

“Well, Sleek! You got here.”

“Afternoon, John! Hello, Aural—glad to see you.”

Sleek shook hands briskly. He was a full head shorter than John Dyne. Both men were dressed in the universal afternoon fashion for both sexes—black and white. But John’s garments were of silk and cotton fabric, and his blond hair was free of covering. Sleek wore soiled black-and-white leather trousers, a jumper of leather which once had been white but now was nearer black from motor-oil, grease and gas-exhaust. His jumper was loose, exposing an inner shirt equally smudged, and revealing his belt and side-stays upon which hung a multiplicity of tiny weapons and scientific equipment.

He tossed his leather hood to the desk. His hair was a brick-red, incongruously smoothed and plastered with pomade, meticulously correct when all the rest of him was disheveled. His hand went instinctively to his hair to verify its correctness as he tossed aside the leather hood—a boyhood peculiarity which had originated his sobriquet of Sleek.

He sat on the desk, swinging his feet. “Anything new? You are on this too, Aural? That’s good—a woman’s wit.”

He was grinning. He seemed set with springs, this wiry little fellow—alert, quick and lithe as a panther in all his movements.

“Father just discharged Yates,” John volunteered. “Quite an altercation—I hope we’ve seen the last of that fellow.”

Sleek’s grin faded. All his attention suddenly came to his companions. “Hope so. . . . Aural, what’s the matter with you?”

It startled her. “I—why—why—”

“She had just started to tell me,” John began, but Sleek checked him.

“You don’t know anything. You haven’t anything new on your face. But Aural has. What’s the matter with you, girl?”

“About Janna Frane—” Aural said reluctantly.

A buzzer on the desk sounded; a wave-sorter’s voice came:

“Call for Aural Granet. Urgent, please.”

The desk grid was glowing with an image—the face of a pretty girl, framed with tumbled black hair. It was Janna Frane. A portion of the room behind her was visible, with one of Joc Vaine’s infant children playing with toys on the floor.

“Aural—Aural, dear—” The governess’ voice was agitated, and there was stark fear on her pale face and in her dark eyes.

Aural sprang to the sender. “Yes, Janna, what is it?”

“Aural, I’m alone in the house here. Only the children—and I—I’m frightened. The—the playroom door here got sealed—I don’t know how—”

Alone in the house, and sealed with the year-old twins in the playroom. One may not be on the brink of death and go unwarned. A natural, inevitable instinct, and the governess had it now.

“Aural—send help—”

She got no further. She screamed, and turned aside. The transmitted scream split the silence of Robert Dyne’s cubby, ten miles from the home of Joc Vaine. The image blurred a trifle as the wave-sorter, alarmed by the scream, flung a connection to the Emergency Investigators. A dozen searching eyes were on the tragic scene in the playroom of Vaine’s home.

The face of the governess dropped away. The length and half the width of the room was visible. The two Vaine infants were playing on the floor, building toys with bits of metal. They were staring up now to where the family robot had appeared from behind a drapery.

“Help! Colly, you, you horrible thing! Go away—get back! Stand back, I tell you!”

Janna’s voice sounded clear. Fighting for her life! An anguish of horror was in her voice and in every line of her figure as she crouched on the floor before the children.

But the giant metal thing did not obey. It came clanking forward on jointed swinging legs. In its outstretched jointed hand, the knife-blade finger had slid out.

An instant of breathless horror. . . . The towering robot stopped, wavered uncertainly, then leaped and pounced upon the crouching girl, with the knife-blade of its hand stabbing into her breast!

John Dyne, Sleek and Aural—and Mekko still with them—were almost the first to reach Vaine’s house. They had rushed to the roof, ignoring the turmoil into which the factory was thrown a moment later by the police wide-cast alarm, and the general call for Joc Vaine. He was on the factory floor at the time; with Robert Dyne he ran for his air-car.

But John and the others were ahead of them. Within a few minutes Sleek’s little car dropped into the main viaduct leading south toward where the great metal ramparts of the city, terraced and spired, reared like a mountain range into the sky. It was dark now. The towers threw monstrous slanting night-shadows upon the city roof. At a fair hundred miles an hour, Sleek’s car skillfully threaded the viaduct traffic, spun around a banked curve and drew up at the latticed gates of Vaine’s house.

The rambling, three-terraced structure was perched on its metal platform well back from the viaduct. Soil laid here gave a garden, luxuriant with vivid flowers this June evening. Upon the balcony-like terraces of the house, flowers and shrubs were profuse against the latticed window-ovals. A peaceful-looking house characteristic of the semi-wealthy in this residential section.

But tragedy was here. Gray-coated officers stood at the illumined portal. The side landing-platform held half a dozen throbbing aëros; a white hospital car winged down and landed with a thump, precariously, among the shrubs of one of the terraces.

Sleek’s glowing insignia, which he flashed from under his jumper, gave his party instant admittance.

“Dead?” he demanded. “Is she dead?”

“Damn, yes,” said the man at the door. “She’s dead as a burned-out coil. God, these robots, when they go wrong—” He sent a shuddering look at the impassive-faced Mekko, which stood obediently behind John. “You taking that thing in with you?”

“Yes,” said Sleek briefly.

They passed into the dim foyer. Footsteps were tramping inside. A child, up the incline on the second level, was wailing dismally. John said: “You wait up there, Aural.” It would keep her out of the playroom.

Outside, other cars were lurching up; other men tramped into the house. From the side upper terrace a newscaster already here, was sending out his blaring wide-cast call: a Dyne robot had just murdered a human. It sent a shudder through John Dyne. This was the end. The factory would be closed now, of course, by Government order. And he thought how his father must feel, to have built a thing which murdered a human.

Mekko suddenly brushed him—just a chance contact, but it shot an instinctive fear through John. What nonsense! Mekko had been his daily companion for years—

The playroom was dim with a pole tube-light. Aural had gone with the children to the adjacent apartment. The girl Janna lay where she had fallen. Men were bending over her: a physician, and police officers. But it was too late.

They had made no move to save her; no need to rush her to the near-by Government laboratories where emergency “deaths” were sometimes revived. This was real death, from which there was no returning. The widening crimson pool under the girl’s pale shoulders and head told even the inexperienced young Dyne that her spirit had gone. The murderer robot lay inert on its back across the room. Diabolical thing of glistening metal! Its unlighted eye-grids stared blankly upward. The frozen smile on its rigid face was gruesome. The chest fuse-box was open, where some one had snatched out the central disk to disconnect it.

One of the officials moved suddenly. “Say, you—however you got in here—order that cursed thing away.”

Mekko was standing over the fallen robot.

“Back!” ordered John Dyne. “Mekko! Over there by the wall. Stand quiet—”

The robot obediently moved away. Other men came into the room. Sleek took no part; he drew John to one side, and they stood watching. Record-images were being made. Print- and scent-detectors were in use.

Sleek gripped at a passing man. “What happened?” he asked.

“Door-slide was sealed. We melted in. The girl—she was weltering as you see her. The children—thank God for that!—weren’t hurt. The cursed robot put up no fight at all. I pulled out the central fuse.” He had the circular disk in his hand. “The thing fell—there where it is now. They’ll be examining it presently. A bad day for the Dynes—”

“I’m John Dyne,” said the young man suddenly.

“Oh, you are?” The officer’s gaze held respect for the Dyne millions, but also a vague animosity. “Your father—”

“He’s coming here with Mr. Vaine. I know, whatever they can do—”

John was floundering.

“Shut up,” said Sleek. “Don’t apologize.”

The confusion in the room went on. Remote human control was mentioned.

John heard himself speaking up quietly: “So far as we know, that could only be done from a distance of less than a mile. Who could have had control of it? Only a member of the household. There are only two adults living in this house—Janna Frane, and Mr. Vaine himself. It could have had no remote control—it must have gone wrong spontaneously.”

John’s sense of honesty made him say it, for he was convinced it was true. But Sleek had no such emotion. He pulled at Dyne. “Shut up, you. . . . Mr. Dyne and Vaine are coming—”

The official demanded: “Where was Vaine at the murder-time?”

“In the Dyne factory—ten miles from here.”

“Shut up,” insisted Sleek. And he added, more softly: “You’re no police tracker, John. Keep out of this. That fellow Yates, for instance—he knew Janna. He often came here visiting—he has been in contact with this robot. How can you say—”

An outside call buzzed into the room. Yates already had been apprehended. His aëro, with him alone in it, had been, at the time of the murder, passing within a mile of the Vaine home, at a scant thousand-foot altitude. The police had blocked his power and brought him down. He would be here presently.

Then Vaine and Robert Dyne arrived. Vaine rushed to the adjoining room, found his children safe with Aural and two nurses who had arrived; then Vaine came into the playroom. . . . John was proud of his father. The elder Dyne towered over most of the men in the room. He offered no excuse. This Dyne-made mechanism had committed the supreme crime. Whatever was wrong with it, Dyne now was determined to discover. His dignity swayed the officials. John could see that there was nothing but respect for him.

“Here is the fuse-disk, Mr. Dyne. You want to vitalize the robot now?”

“Yes, now!” Dyne, with Vaine at his elbow, knelt over the fallen robot. John saw that his father’s fingers were trembling. A sudden hush fell on the room as Dyne plugged the disk into the box-aperture of the metal chest.

The interior current hissed faintly as current circulated. The electronic “blood-stream” of this inert murderous mechanism, revivifying it! The jointed tubes of its legs stirred, twitched. Light came into its eyes. In the silence the rasp of its quivering fingers sounded as they convulsively scratched at the floor.

“Sit up!” Robert Dyne commanded tensely. “I am your master. I order you to sit up.”

The mechanism seemed in working order. It moved. Its torso came erect; it sat with arms bracing behind it.

And then the thing suddenly tried to regain its feet. Abruptly the horrified John saw that his father was struggling with it. Then a dozen men leaped upon the lunging metal giant. Its flailing arms swept them back. John and Sleek were in the mêlée. A brief, horrible combat. . . . John found himself clutching a metal arm; it lifted him bodily from the floor, swung him with its mechanical power as though he were a child. Sleek was clawing at the bulging chest, fumbling for the central fuse. He pulled it. The mechanism wavered, went crashing down with a dozen scrambling men on top of it. . . . One was underneath; he lay insensible as they pried the weight of the thing from him.

“Enough!” shouted the police chief. “You can’t risk that again, Mr. Dyne. . . . Mellon, get that man to the hospital.”

Joc Vaine was at the head of the motionless robot. He panted: “Smash it—no chance like that again. I’ll—smash it now.”

He had the back slide of the head open. His hand was reaching in; another instant, and he would have ripped out the coils and the memory-scrolls, demolishing them.

John jumped at Vaine: “Stop! Don’t do that!”

Vaine desisted. “I thought—better smash it.” The superintendent was breathless. Blood was on his face where the robot’s flailing hand had clipped him in the struggle. “Too great a chance—Mr. Dyne, I think we had better—”

“No!” roared Dyne. “Get that head opened carefully! No chance of danger, you fool, with the fuse-disk out! The human orders it received which caused its past actions will be engraven on the memory-scroll if we can get it out unblurred. You know that! It can be done—”

He and Vaine were in a moment working at the head. John’s attention was distracted. Sleek jerked at him.

“Come here.”

Sleek had pushed Mekko back into a corner of the room. No one else heeded them—the police officials were all watching Dyne and Vaine. One of the robot’s ear-disks was glowing. Aural’s microphonic voice sounded softly—from the adjoining room, through Mekko, she was trying to talk to John.

Again the playroom went into confusion. More of the police had arrived, bringing the captured Georg Yates. They flung him into the center of the room, pounding him with questions.

“Remote control,” said the police chief. “That’s how he did it, if he did it. . . . Stand back, all of you. I’ll have this out of him now.”

Georg Yates climbed to his feet from where they had flung him. The tube-light gleamed on his disheveled hair and pale face, and painted the tense figures of the men who stood in a crescent around the police chief and his prisoner.

“Yates, you were within a mile of this house when Colly, the robot, committed murder. You knew Colly? You have been here before, many times?”

“Yes, I have.”

“And you proposed union with Janna Frane, and she rejected you?”

Yates was recovering his poise. “That’s known to several people.”

“A motive,” said the official. “And you have still another motive—animosity toward Mr. Dyne. To harm him—close his factory—ruin his business—”

“I wish I could!” Yates muttered. “I tell you—all of you—I had nothing to do with this. How could I know that Janna was here alone with the robot?”

“Instruments in your aëro—”

“I had none. Ask these men. They searched me and my car.”

Joc Vaine came forward. “Remote control demands special radio-sending equipment. Was any found on him?”

Nothing of the sort had been found on him, quite evidently.

“I won’t hold you,” said the police chief abruptly. “You are released in your own custody. With a shadow—you don’t object to that, do you?”

“As you please,” said Yates sourly.

The shadow was here in the room. At the chief’s order, one of his men who lurked here invisible, abruptly materialized. He stood near the door, enveloped in his glowing-hooded cloak.

“Franks, stay with this man.”

The under-sight man nodded. His cloak glowed a little brighter, then faded. His figure for an instant was a wraith—then gone. The space where he stood seemed empty.

John Dyne whispered to Sleek: “Why, if he knows he’s got a shadow, he can drop it off easily.”

“That’s what they want to find out,” Sleek returned. “See if he will shake loose this shadow. If he does, and thinks himself alone, the other shadows who will be after him might learn something.”

“Get along, Yates,” the chief commanded. “When we want you, we’ll bring you.”

“I’m obliged,” Yates said sardonically.

He strode from the room. Vaine and Dyne were at the fallen robot’s head. The disk of the memory-scroll came out finally, and Dyne and Vaine departed with it for the factory laboratories.

The official investigation of the room was again in progress. Mekko was still standing with John and Sleek. . . . Aural’s voice sounded: “John—John! Come here!”

No one heeded them as they left the room. Aural was in a room across the padded corridor. She moved away from Vaine’s two children and the two hospital nurses.

“I think I have a clue—wanted you to come with me, secretly.”

“Where are we going?” Sleek demanded, as she led them along the dim corridor. “You want Mekko with us? The damned thing makes so much noise. Shut it up.”

“Quiet, Mekko,” John cautioned. “Walk softly.”

They had passed from the padding of the corridor, through a door and onto a balcony close against the side of the building. On the metal balcony floor Mekko’s feet were clanging; but now its foot-pads came out, and it stalked with noiseless tread. This was the rear of the house; a momentary seclusion was here, for it seemed that most of the turmoil was in front.

Aural whispered: “What I started to tell you, John—Janna hinted that she knew something—some mystery. How much of it she understood or guessed, I don’t know.”

“And she was killed,” Sleek murmured, “because of what she knew, or guessed. That’s obvious. A clue, Aural?”

“She told me she had a little sanctuary where she often sat alone. She hinted of a diary there—”

They had come to the head of a descending incline. Sleek gripped the girl.

“Diary? If only we can find it! Get a clue—follow it on our own line! The devil with this official turmoil! They turn search-beams on everything they do.”

The incline terminated at the mid-level terrace garden behind the house. It was dark here, with only dim starlight filtering through the foliage. Sleek added in a whisper:

“Can’t maintain seclusion here very long. Hurry, Aural.”

Were they already spied upon? Sleek’s vibration-detector was in his hand. It seemed that no one was electrically watching.

John Dyne issued orders to the robot. Mekko was microphonically listening, and with eye-beams swinging from infra-red to ultra-violet, striving to pick up any eavesdropping interference.

John had snatched up an article of Janna’s clothing. He handed it now to Mekko. “Search! Find something like that!” The scent-detectors of the robot’s finger-tips followed the trail of the dead governess, who had so frequently been in this room, here and there, back and forth; finally those finger-tips turned over a small stone, and a thin metal-capped book was revealed.

Sleek pounced upon it. “Good enough, Mekko! You’re best of your kind, that’s evident.”

Sleek’s own scent-detector had proven less delicate than the finger-equipment of Dyne’s robot. He snapped the little instrument back to his belt.

“Let’s get out of here. Nothing else here, Aural? Or do you think—”

“It was all she mentioned,” Aural answered. “Can’t we read now—”

But the book’s pages were blank.

“Invisible vibrator ink,” murmured John.

Quite evidently it was. Janna had been afraid to record her suspicions openly. Sleek tried the fumes of his chlorine gas-gun upon the pages, but still they yielded nothing.

“Come on,” Sleek said. “I can make this visible in my laboratory.”

With the diary in his pocket, Sleek hurried them away. A news-gatherer’s actinic image-beam struck down into the flowery retreat just after they left it.

Sleek chuckled.

“A little late with your images, my friends. You should have been a minute quicker—you’d have had something to project.”

Sleek’s personal laboratory flashed into light as he flung the switch. It was an eerie little place, hung close under the city roof in the North Manhattan business section. Its padded, insulated walls were racked with a multiplicity of instruments and chemical appliances.

A haste was on Sleek now. It communicated to John and Aural. It seemed that they had, here with this diary, a vital clue to the mystery.

Sleek was hardly a minute getting his vibrator connected. It hung in a small bracket over the blank white page of the diary. The vibrations began their faint hum—a low grumble, coming up the scale, gradually to a higher pitch—so rapid and so faint that they were almost inaudible.

John and Aural peered intently. What would the page reveal? Blank still, it was; then suddenly as the vibrations reached the designated pitch, the ink-particles began responding. And now they could read the scrawled writing:

The page ended. A plot against the Government platinum vaults—the great metal reserves of the Federal Government! But when? And—he! Whom did she mean? Some human she suspected?

“Another page!” John urged. “Take the next one.”

Sleek swung the vibrator. . . . Another tense interval.

Disappointment. The glowing letters on the old page were already gone. The new page yielded another entry—evidently made a day following. The thread of thought was not continuous. Sleek and John read:

The writing turned suddenly into such a hasty scrawl that it was barely legible:

The latitude and longitude were given in degrees, minutes and split seconds. A definite meeting-place of criminal robots, led by one labeled James X22X. And the date and specific time—

“That’s tonight!” gasped John Dyne. “Ten p.m. tonight! Here in the city!”

It was now after nine o’clock.

“Who bought James X22X?” Sleek demanded. “Who is the official master of that one? Can we find out?”

“Yes. I’ll call the factory.”

It was excessively hot here in the padded laboratory. Aural was suddenly pale. John at the audiphone heard her say: “I’ll take Mekko, and get some air in the corridor.”

She and the robot left; John and Sleek hardly heeded them.

John put in his call for the factory. There was a delay. . . . Sleek was still working the vibrator, but the diary yielded no more.

“John! What was that?”

Horror was in Sleek’s voice. He cast away the vibrator. He did not wait for John Dyne’s answer, but was rushing for the padded door of the room. And John was after him, for he too had heard it. The faint sound of a girl’s scream. Aural! And a muffled thump. Something falling.

John Dyne was unarmed. Sleek, in those seconds as they dashed across the room, had a flash-gun in his hand, and he thrust another at John. The dim vaulted city corridor ran like a blue-lit tunnel close under the glassite city roof, with this door of Sleek’s laboratory opening directly upon it. . . . The fallen, motionless figure of Mekko lay almost at the threshold—and Aural was gone.

To John Dyne, those next few moments were the most horrible of his life. Aural gone—vanished, here in this city corridor! John found himself dashing frantically around the narrow vaulted space with some dim idea that whoever had assaulted Mekko and stolen the girl might be here, shadowed to invisibility. But within the thirty or forty feet of the corridor length which he covered with his futile, aimless dash, he encountered no one.

“John! Come back here! What in the devil—”

Sleek had run to the nearest alarm-post. The actinic glare of the public alarm-light bathed all this vicinity with dazzling white illumination. No shadow-clad figures could withstand it.

The corridor-block was empty. Pedestrians on the near-by catwalks stood stricken with curiosity. Through the side corridor windows, the blur of a monorail tram went by, a level or so down, with passengers craning curiously from all its ovals.

Sleek clutched at the returning John Dyne. “They went down—this way—down this lift-shaft—”

The vertical car was just reaching the bottom of the shaft. The indicator showed its stop. Sleek summoned it back. It came empty.

“They went—that way, probably,” Sleek repeated.

But it was too late to stop them. The lowest level here, Sleek knew, was a maelstrom of traffic at this hour. The fugitives would mingle and be swallowed up in an instant.

Aural gone! The shock of it dulled John Dyne. Swift things happening around him, dulled and blurred. The local street-alarm siren was shrieking its warning. Through the glare officers came running. The street image-lenses were picking up the scene visibly and audibly from the sound-disk, transmitting it to police headquarters, and to the news-agencies.

A mob would be here in a moment—the confusion of publicity.

“Accident!” roared Sleek. “Robot damaged! That’s all! Here, you men—help us drag this thing into my office.”

Half a dozen of them tugged and pulled, sliding the heavy metal form of the inert Mekko through Sleek’s doorway.

“That’s all. Thanks.” He showed them his official insignia. “Well—don’t you see I’m telling you to get out! I’ll notify Headquarters. Conduct your damned investigations outside.”

Sleek was panting. He banged his padded door upon the white glare and the turmoil of the arriving throng.

“John, seal that door! Shoot on my barrage! We’ve got to have quiet. Seclusion! Lord, man, this is serious.”

Serious! Aural gone! John Dyne obeyed in a stupor of horror. He could drive a plane through the stratosphere at eight hundred an hour; whirl and dive it with every manner of daredevil tactic; but contact with crime was new to him. A mystery in his father’s factory—that was a stimulating adventure. The murder of a girl governess, a girl whom he hardly knew—that had been a shock. But this, Aural attacked—this struck at his heart in a fashion wholly different. He stood dulled with confusion, obeying his companion’s orders and watching, marveling vaguely at the swift methodical efficiency which in this crisis had descended upon Sleek.

“Police Headquarters 25, please. In a rush!”

Over the audiphone Sleek told officials what had happened. “Lift, Plaza 102, descended to lowest level. Three minutes ago. . . . I think the girl was taken that way. . . . Go ahead. . . . Yes, a general alarm. But see here—don’t chase them too closely—don’t want them to drill her with a ray, do you? We want her back alive, not dead!”

This stung John Dyne into coherency of thought.

“Sleek, don’t let them—”

Sleek banged up the audiphone. “Don’t worry; they’re not nit-wits. Anyhow, they won’t do much. Most of it will be light and noise. . . . It’s our job, Johnny. Follow our own clues—in a rush now.”

A sudden calmness came to John Dyne. “You tell me what to do,” he said crisply. “All new to me—this sort of thing. Only tell me—and I’ll do it.”

“Right! Take a look at that Mekko—we’ll need it. It’s a devilishly handy thing to have with us. If you know anything about robot mechanics, use it now, Johnny. Get the thing to working again.”

John Dyne bent over the deranged mechanism. The body shell seemed hardly dented. The central fuse was intact. The lightless eyes were open. He opened the back slide of the head. A tiny interior tube was glowing. The mechanisms here seemed all right; and he did not dare touch them—they were too intricate and delicate for his unofficial knowledge.

Sleek meanwhile was methodically active. General messages were flooding in; the drone of the announcer’s voice filled the silent shadowed laboratory. Then Sleek shut the instrument off. John heard him connecting with the Dyne factory, asking the stock-record man to give the history of the robot James X22X.

“All right, I’ll hold the wave. But look it up in a hurry.—Can you fix the thing, John?”

“I don’t know. Are Father and Mr. Vaine there?”

“No. They haven’t arrived yet.”

This sent a new perturbation over John Dyne. His father and the factory superintendent had left Vaine’s home for the factory, with the memory-scroll of the murderer mechanism, Colly. They had had far more time than necessary to get there. Where were they?

Then came the news. A call from Headquarters. Sleek held both audiphones at once.

“Yes—of course I want it. John Dyne is here. I’ll take the message for him. . . . The devil! Not hurt badly?—It’s not serious, John! Don’t get excited. Not Aural—your father. . . . No, I’m not talking to you, go on. What else? . . . Right! Thanks.”

He cut Headquarters off. The elder Dyne and Joc Vaine had been attacked by robots on the way to the factory. The memory-scroll of Colly was irrevocably smashed. Joc Vaine was gone—abducted. John’s father was superficially hurt—knocked unconscious.

“He’s recovered now, John. He’s just arriving at the factory. . . . I’ll have him on this other wave in a minute.”

Sleek gestured John away. “Get Mekko working, can’t you? I’ll talk to your father. No time—with Aural gone—”

“Mekko is working.” John Dyne at that moment had found a loose connection, a vital one, in the back of the neck, where the motivating impulses came from the head. The jar of the fall evidently loosened the nerve-wire. Mekko’s interior was slowly warming now with the insulating current.

“Fixed it?” demanded Sleek. “Good enough. Stay with it, Johnny.—Mr. Dyne? Hello! What happened to you?” A long interval while John held his breath, listening to his father’s microphonic voice. The image-mirror showed Dyne’s pale face and bandaged head.

Then Sleek was telling what had happened to them. “You stay at the factory, will you, Mr. Dyne? . . . Yes, might need you at any time. An’ listen—hurry up your clerk on those records of your robot tagged James X22X. . . Can’t tell you now. Too rushed. . . . Yes, wave me back. We’ll be here for a few minutes yet.”

He slammed up—came at John. “Your father’s all right. Vaine’s gone now! That memory-scroll smashed! They’re right after us, whoever they are. Widespread plot—opening up right this minute. Obvious, isn’t it? Everything breaking on us all at once. We’ve fallen into something big planned for tonight.”

An audiphone buzzed again; the elder Dyne, at the factory, called Sleek back. The robot James X22X was an expensive type, similar to Mekko. It had been sold and delivered two years ago to a wealthy man named William Benning.

“I know him!” Sleek exclaimed. “He’s got a criminal record. Worked in the Government platinum-coin factory. Arrested for conspiracy five or six years ago.”

It hooked together. Janna’s diary mentioned a plot against the Government platinum vaults. Benning was at liberty now. Not wanted by the police, but under constant surveillance. He lived here in Great New York; the robot James X22X was his servant and frequent companion.

“Mr. Dyne, call Police Headquarters. Get me the present whereabouts of this fellow Benning and his robot.” Again Sleek slammed up. “Well, there’s the name of one of the humans in this: William Benning.”

Despair was flooding John Dyne. It seemed that he ought to rush somewhere, do something that would bring Aural back.

“Sleek—” he tried to voice it; but Sleek cut him short.

“All the police shadows in the city are after her at this minute.”

A fruitless chase—time was passing with no result. John stood with Mekko. It seemed an eternity here, with Sleek dispatching everything as fast as he could; but in reality it was only a few minutes.

Two audiphones were buzzing now and Sleek received the report of the present whereabouts of the ex-criminal William Benning and his robot James X22X. Benning had been under routine police surveillance. An hour ago the robot was with his master—and both had shaken off their shadows.

“But we hope to re-locate them presently.”

“Good!” said Sleek sarcastically, as he disconnected. “I’m glad you have hope, anyway.”

The other audiphone was bringing routine police news. “Georg Yates, paroled an hour ago, with shadow, is missing. Report of the shadows explaining the unfortunate incident, will be broadcast presently. Additional shadows assigned; hope soon to re-locate—”

“Shut up!” roared Sleek. He slammed away the instrument. “You blame me, Johnny, for going in this alone?”

“But what—”

Sleek stood before him. “Janna Frane’s diary says at ten o’clock tonight, a meeting of these criminal robots, led by James X22X. That robot is missing—gone there, no doubt. Yates is missing. And Benning. Whatever this is, John—that’s all the clue we’ve got. Human, or robots—or both—they’ve been warned now. The murder of Janna set the whole city after them. Then your father and Vaine—they had a vital clue. They were attacked—Vaine abducted—the clue destroyed. And now they’ve taken Aural away—”

Had they killed Aural? John Dyne thrust away the thought. Sleek had dashed across the room; he was searching among his effects, but still talking.

“We’ve got the time and the place of this meeting of robots. . . . Where the devil did I put that map? . . . What time is it now, Johnny?”

“Nine-thirty-seven.”

“We’ve got twenty-three minutes. Here’s the map. Come here—help me locate this depth and latitude and longitude.”

The figures which Janna’s diary had given placed the spot fairly accurately on Sleek’s large-scale map of the city.

“We can guess it within a hundred feet or so,” Sleek declared. “Here’s where it should be.”

It was to the southwest, past Manhattan Island, in the artificial land which once had been meadow and swamp. The depth—twenty-five feet—evidently referred to the distance below ground-level.

Sleek handed John Dyne a shadow-cloak and vibration-gun. “Best thing to use against both men and robots.”

It was a short-range weapon. Its ultra-rapid vibratory beam would strike a man into unconsciousness or burn out the coils of a robot at a distance of twenty or thirty feet.

“We’ll take my aëro-car, John. It’s racked overhead. Drop it somewhere near this meeting-place—”

They were ready in a moment. John tested his cloak. The current faintly sang through it. His figure faded to invisibility.

“Correct,” said Sleek. “Snap it on—no reason to start off like that.”

Mekko now held a shadow-cloak folded across its metal arm. John felt suddenly with intensified clearness the sinister aspect of modern criminality. Invisible enemies and invisible mechanisms could be lurking everywhere—enemies fortified by all the devices of science. This great roaring metal city, what one could see of it was so little! An army of shadow-police seeking other shadows—an underworld of events transpiring unseen—

Sleek’s padded door swung open; the turmoil of the city corridor surged at them. The alarm-light was still on. The crowd of pedestrians was still here, held back by uniformed men. Photo-images were being made and flung to the radio-receivers in a million homes.

“Light and noise,” Sleek muttered. “Nothing much else.” He gripped an official who was standing guard over their door.

“Send a message for me, will you? Can you send in code from here?”

The man could.

“Tell Traffic Headquarters I’m going in my plane-car on a secret mission. I want to be let alone, understand? I’ll be without lights. If any tower-man hails me, I’ll flash two reds and two whites.” Sleek was whispering it vehemently. “That will identify me. They must let me alone, understand?”

“Yes sir.”

“An’ listen—get this straight: I’ve been warned of a possible plot against the Government platinum-coin factory. I don’t know if it means the one in Great New York or the one in Washington. Have the press-rooms guarded—and particularly the storage vaults.”

The guard’s jaw dropped. “A plot against—”

“You heard me. Don’t be a nit-wit! Warn them. It might be a big attack—an assault on the vaults. . . . No, I don’t know when. Tonight, maybe.”

Sleek drew John Dyne and Mekko forward, up an incline to the city roof. The outer air seemed a blessed relief to John. A gentle night breeze was blowing. It was a clear night; the deep purple sky was cloudless, strewn thick with stars. The traffic was normal overhead—moving, orderly lights at the different levels through which the traffic-towers sent up their guiding colored beams.

Sleek started across a catwalk toward where his car was racked on its small official landing-stage. The terraced glassite roof stretched like a great rumpled, disordered sheet, propped by the city buildings underneath as though by the knees of sleeping Titans. This upper surface was dotted with pot-bellied water-towers, with tangles of electric cables and water conduits lying like strewn pythons; the thousands of little ventilators were like perking ears, listening into the wind.

There was no surface traffic on the roof. Barred to the public, save at the occasional landing-stages, there were only official patrol cars passing on monorail tracks. . . . Sleek was at once stopped; but his insignia passed them. They climbed into the pit of his small air-car.

The electrolysis engine hissed like an angry snake. From the side-ports of the car the rocket-streams of decomposed air shot out. The magnetic rotary motors whirled the overhead helicopter blades. The car rose and slid forward.

“Nine-fifty-one,” said Sleek. “We’ve got nine minutes. About twenty miles, wouldn’t you say, Johnny? With the ascent and landing, we’ll have to hurry.”

John Dyne, at the controls, lifted the car swiftly into the high fast-traffic lanes, and with full power slid forward through the starlight.

“Lights off, Johnny?” Sleek asked.

“Yes.”

They had not been challenged. At thirty thousand feet of altitude, the city lay sprawled like a huge metal octopus, with its tentacles reaching out into all the surrounding country. The roof covered only middle and lower Manhattan. But where it ended, the bridges and viaducts spanned the rivers like a rank vine-growth, so that the sullen, harnessed water was almost subterranean.

The open water toward the Staten district gleamed with the colored signal-lights of the traffic. John Dyne had swung high over it and to the right. The Jersey lowlands were a mass of low metal buildings; stacks like spires exhaling smoke and half-burned gases stood upon some of them, but most were factories wholly electric-powered. Flashes of blue glare spat and flickered.

Vast industrial activity here. The flat, muddy rivers were overgrown with viaducts. Monorail tracks were everywhere—vivid lines of colored light-markers—and moving lights which showed the haulers in transit.

This was the surface aspect. But John Dyne knew how very small a part was visible. There were cellars and sub-surface corridors laboriously dammed against the seeping water of the lowlands; a labyrinth underground and underwater.

“Where shall we land?” he whispered to Sleek. “You got our range?”

“Yes.” Sleek’s instruments showed the seconds of latitude and longitude. The aëro-car now was almost over the exact spot they were seeking. With his optical distance-shortener, John Dyne gazed down over the pit-rail. In all this hive of evening industrial activity, it seemed that directly under them was a spot dark and silent—a metal structure closed, or not in use by night. It was a flat, rambling building with a low-pitched roof largely of glassite windows. A high palisade enclosed a work-yard of several acres, in which idle machinery stood about.

A strange aspect of darkness and neglect was here. John Dyne held the car poised by the helicopters, and was gradually drifting downward.

Sleek asked: “What factory is it?”

Then John Dyne saw an unillumined sign and was able to read its tube-letters.

The place they were seeking! Were the criminal robots, led by James X22X, whose master was William Benning, who owned this factory, meeting here now? How were they arriving?

It was three minutes of ten. A light showed bobbing to the surface of the river which passed near the edge of the factory palisade. An underwater carrier came briefly to the surface. Something dark climbed from it to the dark jetty; the tiny vessel sank and was gone. The dark metal shape of a robot slunk back from the jetty, moved through a gate of the palisade and disappeared. And in a minute another boat came.

The robots were gathering here, coming by water! John Dyne saw a little twenty-foot square of open space. He lowered their unlighted car into it. There seemed no alarm. They dropped to the ground. The dark building and the dark shapes of giant magnetic cranes standing in the yard loomed around them.

“Good enough,” whispered Sleek. “Drape that cloak over Mekko. Johnny, we’ll go round the front—get inside. Follow us, Mekko.”

With hooded shadow-cloaks faintly humming, the two humans and their giant machine stood together.

“Don’t get separated,” Sleek murmured. “I’ll lead. I’ll make just a little noise, so you can follow me.”

Vibration-gun in hand, John Dyne moved after the invisible form of Sleek, with Mekko behind. They crept along the shadowed side of the building toward its front entrance. Would there be a guard?

Objects were visibly blurred to John Dyne as he gazed through his vibrating visor-pane. It was confusing. And the faint snapping which Sleek was making to guide him was blurred. . . . They turned the corner of the building. . . . John Dyne suddenly became aware of the gray figure of a robot towering in an open door-oval. Its eye-lenses were luminous small beams, sweeping the yard. Evidently it was guarding this doorway.

Dyne checked his advance. Mekko, from behind, bumped into him. They stood an instant. The other robot was no more than ten feet away. It suddenly gave a lunge, and fell forward on its face. And Sleek’s low voice sounded:

“Got it! John, come here! Hurry!”

Sleek snapped off his current; his figure materialized; he was holding the central disk of the robot in his gloved hand. The robot lay inert. It was an older type than Mekko, but very similar in aspect.

“Got to get it hidden,” Sleek added. “Before any others come! Hurry it! Mekko, drag it in.”

The door oval to the dark factory yawned beside them. Mekko dragged the metal burden into a black interior. The label engraved on its chest-plate was Rex Y40.

Sleek abruptly whispered: “Here they come! Hide! John, listen—you keep Mekko close by you. If any human comes, we’ll jump on him. Or if these robots bring Aural—”

It sent a shudder over John Dyne. Aural in the grip of criminal machines! Two robots came together and stalked through the door into the interior darkness, their eye-beams swaying before them.

They seemed to disappear down an inclined passage. . . . Then three came. . . . An interval. No more arrivals. No humans. No sign of Aural.

A distant clanking sounded inside the building. Sleek whispered against John Dyne’s ear: “Let’s go down and take a look; we’re invisible—unless the damned things scent us.”

It was a chance. And Aural might be down there. They left Mekko with a command to remain motionless. With shadow-cloaks electronified, they started down the incline. It was not necessary to go far.

Eerie scene! A dim cellar. Nothing human here. Fifty or more erect and clanking mechanisms were ranged around the room. Under remote human control, unquestionably. One of them, identical in model with Mekko, moved around from one robot to the next. It seemed tabulating them.

John Dyne whispered: “That’s probably James X22X. If we could capture it—get its memory-scroll—”

The robots were starting upward! Sleek and John hastily retreated. With Mekko again beside them, they crouched in the upper room while the clanking machines went past.

John Dyne’s heart leaped. Fortunate chance—James X22X came last! The others had gone and were out of sight in the outer darkness.

Dyne murmured: “Mekko, walk to that robot. Pull out its main chest-fuse.”

As Dyne spoke, he snatched off Mekko’s invisible cloak. . . . The enemy robot stopped its advance as Mekko stood before it. There was a sudden scuffle—then the sound of clanking metal against the floor. One of the robots had fallen. But which one?

Dyne and Sleek dashed forward. Mekko stood with swaying eye-beams. The huge bulk of the other machine lay inert.

“Good!” Dyne exclaimed. “Move away, Mekko.”

The machine moved a step or two. . . . Sleek cautiously went outside. In a moment he was back. A large underwater vessel—it seemed radio-controlled, without human occupants—had quietly come and taken the assembled robots away. But whither?

Sleek said: “These human criminals certainly keep themselves well in the background, don’t they? Johnny, the scroll of this James ought to have a complete record of its orders. Oughtn’t it? Can’t you get the scroll out?”

Dyne fumbled at the back of the thing’s head, and Sleek bent with him. Sleek added:

“It’s under remote control, of course. And a damned sight further remote control than a mile, probably.”

Then Dyne stood up. “I can’t remove the scroll. Afraid I’ll smash something. But Father can—in a few minutes. He can learn a lot from this machine—suppose we rush it to the factory?”

It seemed the best thing to do. The elder Dyne was waiting at the Dyne plant. He could be signaled, and in a moment or two could come up to their car in the air and join them. That would be quicker; they could start at once for any destination which was revealed. It would not take Dyne long to remove this thing’s memory-disk—and with the proper magnifying instruments, he could read it. If only Joc Vaine were available to help! But John Dyne and Sleek had little hope that Vaine would have reappeared. Vaine, like Aural herself, had vanished; caught by these mysterious human criminals who were keeping themselves so carefully under cover, with only their robots apparently in action. And it was obvious now that if the robots were under control, it was at far greater range than the mile limit for which they were originally designed.

Mekko lifted the five-hundred-pound burden of the inert James X22X, swung it horizontally across outstretched arms. They moved from the shadowed room. All the other robots had gone; there seemed nothing moving in the pale starlit yard; and there had been no alarm from the neighboring factories. In a moment, with John Dyne at the controls, Sleek’s air-car was again in flight.

A traffic director from the Hoboken base sent them up his query-light; but Sleek answered with his red-and-white signal, and the peremptory search-beam swung away.

For hardly more than ten minutes they darted high over the ramparts of Manhattan; then they were again above the Dyne factory. Its spreading dark buildings showed with occasional tiny lights; a single white glare flooded the roof landing-field.

Sleek’s audiphone had already established connection.

“Mr. Dyne? This is Sleek. We’re in my car—lightless—at thirty-five thousand feet altitude, almost over you. You alone there?”

“Yes. Alone in my cubby. Sleek—”

“Any word from Aural, or Joc Vaine?”

John Dyne held his breath for the answer, but it was negative. Sleek told what they had done. The elder Dyne must bring his necessary instruments for reading this robot’s memory-scroll.

“Come alone,” Sleek warned.

“Of course.”

He disconnected. John Dyne held the car poised in the thirty-thousand-foot lane. High overhead a through mail liner sailed majestically past, its sides dotted with rows of colored lights. In the silence of this upper air, strains of music from its deck floated down. It passed southward and away.

“There he comes, Johnny! Hold us. I’ll give him our hull-lights.”

Far down in the blob of floodlights which marked the roof of the Dyne factory, the tiny lights of a helicopter car were visible. A moment, and then it was ascending. It came straight up—a small boarding tender—hardly more than a basket hanging under its whirling blades. The bare-headed, black-and-white-garbed figure of the elder Dyne showed in it. . . . It came level with them. Its suction arm-beam came out, made contact with the metal plate in the side-hull of Sleek’s car. Then Dyne flung across the span-rail; and in a moment he was aboard.

“So that’s your captive!” He stood a trifle out of breath, gazing down at the motionless James X22X—this thing which he had designed, built and sold, and which now was a mechanical criminal. He added grimly: “We’ll see.” He laid his black leather case on the cockpit floor.

There had been a confusion of greetings and exchange of questions as he came aboard. No one noticed the vague shadow which had come with him; silently it eluded the occupants of the pit and now was crouching forward.

“What shall we do with your car?” Sleek demanded. John Dyne had returned to the controls. “Cast it loose—let it crash. What else? We don’t want it tagged to us up here.”

The tender’s helicopter blades were slowly revolving. Sleek pried loose the suction disk. The tender broke connection. It hovered a moment, and then began sliding downward.

“Go ahead, Father,” John urged. “Get that memory-scroll out of the cursed thing. I’ll fly us—”

“Where?” demanded Sleek. “How can we start for anywhere, when we have no destination? Help your father, Johnny. Mr. Dyne, can I—”

They were all three bending at the head of the inert robot; Dyne was opening the machine’s skull-panel.

No chance for any of them to see the shadow which now was materializing into a vague, hooded shape behind them—or to hear the faint, padding steps. And then came the voice:

“Don’t move! Don’t any of you move! I’ve got you all covered!”

It was Georg Yates. The hooded shape of him had materialized into a dark but visible solidity, as he stood with a spreading-muzzle vibration-gun covering them all.

John Dyne with the others around him, crouched stricken. The weapons in his waist pouches could have been a thousand miles away, for all their availability. Yates was adding, briskly:

“Raise your hands over your heads, all of you.”

“Up!” murmured Sleek. “Don’t fool with this fellow.”

Yates flung back his hood and laughed. “What’s that other robot lying there?”

“Its label is James,” said Sleek shortly.

“Benning’s robot! Thought you’d get the head open, did you? How you got possession of it I don’t know, but I got you just in time, didn’t I? All of you—at once—quite a piece of luck.”

He was nimbly stripping Sleek of his weapons. There was nothing John Dyne could see to do. Yates, for all his sardonic grin, was wholly watchful, with the muzzle of his weapon leveled close against the head of the elder Dyne. A moment, and all their weapons were tossed to a far corner of the pit. John saw that the car was hanging nearly poised; its helicopter engine running smoothly. The tender in which his father and Yates had ascended was dropping slowly down, but it had not yet crashed.

Yates said: “You, Sleek Adam—you’re a trailer—get out your manacles. One move, and I’ll blast open the skull of Mr. Dyne. . . . Get that damn’ robot’s eyes off me, will you?”

Obediently Mekko gazed away. A moment more, and Yates had John’s father and Sleek, stripped of his weapons, manacled and shoved to the floor against the side of the pit.

“You lie there . . . You, John, take the controls. Fly us.”

“Where?” demanded John Dyne. He seated himself, and turning with a swift gaze, met the muzzle-grid of Yates’ menacing weapon.

“Fly us down the bay. Twenty-thousand-foot lane. Damnation, it’s cold in here—haven’t you got heaters?”

The interior of the pit was chilling; John Dyne switched on the heaters, started the horizontal propellers and headed the car southeast.

Mekko’s eye-beams were swinging around the pit. Yates, with his weapon still upon John Dyne, watchfully turned his head.

“What’s the name of this robot?”

“Mekko,” said John.

“Oh, yes. I remember that one of yours. I want control of it now. Don’t impede me. Where is the fuse-disk of James?”

John said: “Mekko has it.”

The machine obeyed Yates now. It stooped and plugged the fuse-disk into the other robot’s chest. John could see his father and Sleek where they were lying docile, but alertly watching, and Sleek was whispering something vehemently. John headed the car with a long descent to the twenty-thousand-foot lane, with half his attention to the scene through the visor-panes, and half upon Yates and the pit interior.

The car was doing three hundred miles an hour now. Already they were slanting over the metal terraces of the congested Brooklyn district. The car was without signal-lights. Would they be signaled? John hoped so. Yates would not know the signal-combination which Sleek had wide-cast to all traffic directors. Without it, when challenged, the car might be stopped and brought down with its power summarily cut off.

But no challenge came. And as though Yates were reading John’s thoughts, he said abruptly:

“Better swing us up. Don’t want anybody after us.”

The moonless night was getting darker. Ahead to the southeast over the ocean, heavy dark clouds now were visible. A swift summer storm. Yet to John Dyne there was something strange about those suddenly appearing clouds.

He demanded abruptly: “Am I heading right?”

“Yes. I want you to make a wide circle—out over Coney Field—over the ocean—come back cutting over the Highlands. Keep us well up, an’ don’t go so damn’ fast. What’s your hurry?”

“You ought to know that. I don’t,” said John Dyne. “What are you doing with us, anyway? You’re a fool, Yates. You can’t hold us like this.”

But Yates ignored it. The robot James had revivified; it was sitting up now, facing Mekko. Yates ordered:

“Mekko, sit down! James, you sit in front of it!”

John Dyne saw, in the shadows across the pit, the two giant machines taking their positions. Yates had moved away; and suddenly Sleek had hitched himself here beside John. And Sleek whispered:

“Your father is going to watch his chance to change the control-registry on Mekko—to give it solely to me, with intensified audibility reception. Just a chance. . . . I’ve got a plan—I’ll be able to whisper commands to Mekko. Don’t you give any! You keep off!”

Sleek hitched himself away. Yates had been peering at the scene beneath the ship, and had not noticed Sleek. He came now and sat beside John Dyne.

“Everything correct,” he grinned. “So I can’t make away with you like this, can’t I? You watch me.”

But whither was he taking them? He seemed confident. He had taken off his shadow-cloak now; he cast his glance over the pit, and then weapon in hand sat on the metal bench beside John Dyne. He was evidently wholly pleased with himself. He chuckled.

“This will surprise them. . . . Not so fast, John. Cut us down to a hundred.”

They had passed high over the tiny lights which marked the main Great New York landing-field near Coney; and now the dark spread of the ocean lay beneath them. Lights outlined an occasional surface ship. The lower air-lanes were dotted with sparse local traffic; to the right the great beacon of the Hook swung its lazy white beam. . . .

John Dyne had swung them some twenty miles to sea and now was cutting back with a slow circle to the right. The night had steadily become more overcast. A haze was in the lower air. The bay, the Narrows, and the upper harbor were half obscured now. And above the haze, threatening black clouds were gathered. John gazed at them silently; and suddenly it occurred to him that they were artificial. A green tint was on them. Was something hidden up there in those clouds, illicitly controlling the weather here tonight?

Suddenly he understood. He saw that Sleek and his father were gesturing toward the dome-roof of the pit, through which the clouds were visible, and were whispering about it. These criminals had their hiding-place in a stratosphere vehicle! A bandit ship! It had come down now, gathering these concealing cloud-masses. Bandits who, with a long-range remote control of their robots, were sending their criminal machines upon some errand of crime in the city, while the criminals themselves remained aloft safely hidden.

John Dyne voiced his thought, and Yates laughed sardonically. “Clever, aren’t you? Well, I don’t mind telling you that’s what we’re doing. Waiting for the treasure to be brought up.”

The Government platinum vaults, in lower Manhattan! The whole plot was clear to John Dyne now. The robots had been mechanically altered so that they were capable of criminality. One by one tonight, in the homes of their criminal masters, they had been diverted from their domestic tasks and sent to the meeting-place at Benning’s factory—taken there in a sub-water vessel, itself undoubtedly remotely controlled, to the vicinity of the Government platinum factory.

A sudden raid! Machines, hidden with shadow-cloaks, with no human fear of death or injury to withhold them, with gigantic mechanical power, and with the deadly weapons of humans! John Dyne could imagine this sudden night assault upon the unwary routine guards at the vaults, which in a hundred years had never had an attack.

Yates was saying triumphantly: “Oh, they’ll get it! Abandon the sub-water vessel—bah, the fool police will find it submerged off the Battery wall tomorrow. Those robots—with the hydrogen heat-torches your father so kindly built into them—can drill their way into the vaults in a minute or two.”

And then, each with his easily carried five-hundred-pound ingot of the treasure, the robots would swarm upward from the roof in portable helicopters; swarm up like Titan insects into the lowering black cloud and be taken aboard the waiting aëro where their human masters had been lurking in safety!

Yates was fatuously telling it to John Dyne—fatuously, because what Yates did not know was that Sleek had already given warning of a possible plot against the vaults. Had the officials heeded that warning? Gazing now toward the far-distant lights of the giant city which showed blurred and dim through the green haze, John saw that the clouds were concentrating over Manhattan. Surely the official weather-control station—especially in the face of Sleek’s warning—would be aware that this was illicit, artificial weather! The Government meteorological controls would soon begin dispelling that haze and those clouds. It seemed even now, that far over Jersey, the weather-control station of the Metropolitan District was getting into action, for the luminous aura of its moisture-absorbing rays seemed visible. And even out here over the ocean, there seemed an echo of the hum of the vibratory weather beams. That cloud would drop its rain soon, and slowly dissipate.

But if John was right in these assumptions, Yates did not seem to notice what was transpiring.

He was saying:

“Thought they had me, didn’t they? Nipping me in because I was flying near where that Janna girl was murdered! I had nothing to do with it. The Chief—and he was miles away—”

“Who’s the Chief?” John cut in.

“You’ll find out soon enough. Thought they had me—putting a shadow on me! By the gods, easiest thing I did was nip that shadow an’ take his cloak, an’ head back for the Dyne factory where I thought you people would be most active.” He chuckled again, and added: “Which, as it turned out, was right. That police shadow probably doesn’t yet know what hit him—”

“Any fool could do that to a police shadow,” came sourly from Sleek across the pit. John saw that as Sleek held Yates’ attention, the elder Dyne had shifted himself to the motionless robots. Was he able to make the adjustments on Mekko? In a moment he had moved away again.

Sleek was taunting Yates. “You got us—but how are you going to get away with us? An’ look here—where’s that girl Aural?”

John Dyne held his breath, with his heart pounding in his throat. Did Yates know?

“Safe enough,” said Yates; and it seemed as though the world had opened up again to John. “Safe enough—much good it will do you, John Dyne! I’ve got my ideas for her. I told the Chief—”

He checked himself suddenly. Out over distant Manhattan a commotion was beginning which was too obvious to be ignored. All of them in the pit turned to gaze at it. Traffic tower beams were focusing upon a single point; and through the haze the white glare of alarm-lights was radiating up from the streets in all the vicinity of the Lower City, north of the Battery Wall.

“See it?” Sleek waved triumphantly. “There you are, Yates. Looks as though your little plot might have gone short-circuited, doesn’t it?”

Yates sat staring, his smile of triumph faded, and a look of incredulous astonishment on his face. The elder Dyne said:

“Got them, by heavens—looks like that. Yates, you’d better let John fly us back to the factory. If you want to escape, we’ll let you go. We’ll say nothing—”

Yates found his voice. “Shut up, you! What you’ll do doesn’t interest me.”

“Let’s see it closer,” Sleek urged. “I’ve got a shadow-box there by John, if you want to tune it in. Get it out, Johnny. Lock our controls. They don’t need you, with us flying slow out here like this.”

They were still ten miles or so from the Hook, and in the fifteen-thousand-foot lane. The muzzle of Yates’ weapon was still upon John Dyne.

“Shall I?” John demanded.

“Yes,” said Yates. “Let’s see it. Something strange off there—”

The black storm-clouds seemed lowering closer above Manhattan; and all the distance between was a murk. John locked the controls and rose to his feet. The shadow-box image-receiver was under the instrument panel just beyond where Yates was sitting. Across the pit, the elder Dyne and Sleek lay half twisted upright to gaze through the side visor-panes; and not far from them, Mekko was backed against the wall, with James fronting it.

John Dyne bent, gripped the small black box of the shadow-projector. He could see Yates’ form just over him. Their one antagonist here! His interest was upon the distant lights. A sudden impulse swept John. One leap now! If he could strike the vibration-gun from Yates’ hand—leap upon him, seize him.

Abruptly Yates demanded: “What are you doing down there?”

“Getting out the shadow-box. Is the murk getting thicker? I don’t know if I can bring images through it.”

John suddenly rose outward and up. But Yates was upon him.

“No, you don’t! Back out there! Give me that box!”

Hardly for an instant had Yates relaxed; he was aware always of his danger. “Get over to the controls—one more move like that, an’ I’ll lay you out with your head ripped open.”

John put the box on the control-seat. “Suit yourself. Can you operate it?”

“Yes. Get back there. . . . What in the devil—”

From the robots across the shadowy pit came the sound of sudden scuffle! They seemed entangled—fighting! Yates was on his feet; he swung his weapon to range across the pit; and then back abruptly at John Dyne. And he shouted: “James! Hold him!”

The scuffle lasted only an instant. A huge metal form went down with a crash.

“James—” shouted Yates again.

The robot which was erect swung obediently around. John Dyne saw that Mekko lay inert, disconnected.

Yates swung back on John Dyne. “Get there at your levers. Hold us where we are. I’ll get us the images.—James, leave that damned thing disconnected. Don’t move from where you are until I tell you.”

The robot stood motionless.

Yates was working over the box. He laid his weapon on the bench; but it was close to his hand. He was wholly alert. Whatever opportunity there had been, was gone now.

Like all of them, John Dyne gave his attention to the shadows which Yates was trying to project upon the dark pit-dome overhead. Through the side-visors the far-away blurred lights showed that the Lower City still was in alarm.

Yates swung the current into the box, with Sleek calling directions. He caught the range. The three-foot cube of the image-scene showed upon the concave roof of the pit.

“You got it,” said Sleek. “Blurred—that’s the murk. Hold it—they’ll clarify.”

The little gray-black shadows were blurred, almost formless. But the Lower City metal buildings were visible, and the beveled terraces and the roof at the old Wall Street corridor. . . .

“South a little,” Sleek directed. “You nit-wit! Don’t you know the Treasury roof when you see it from the air?”

They had caught the radiations from a stationary lens-finder on a neighboring roof-cornice. It was as though they were looking down upon the low, flat Treasury roof, from a higher altitude to the side. A blurred, three-dimensional scene, diminished here into a little three-foot cube. Then it clarified.

A white alarm-light bathed the Treasury roof. Figures were there—a group of robots clustered in an angle of the roof-parapet. Bolts from their flash-guns spat outward. It seemed, too, that they were trying to get helicopters assembled. One rose sluggishly a dozen feet, but sagged back. Embattled machinery! The sight of it sent a shudder through John Dyne as he sat staring. The human guards were evidently upon the opposite side of the roof. From behind a ventilating tower an occasional bolt came darting. . . . Through the central door to the building below other robots came swarming. It seemed that a hundred were here. They were stooped, bearing their burden of the heavy gray-white ingots of the precious metal. . . . The guards made a rush—

Soundless scene of little shadows here on the dome roof! But John Dyne could imagine the crack of the bolts, the humming of the vibration-beams, the clatter of the robots as they fell. He could see them fall, tumbling with their burdens. From some of them the deranged heat-torch of their auxiliary arm, which down in the vaults they had been using, now spat forth its fire, sizzling against their bodies, fusing the metal with a shower of sparks.

It was too small an image here for many details. Tiny shadows mingling on a tiny gray roof. . . . Some of the guards were falling. It seemed to John Dyne that he saw a raging maniacal mechanism with its metal torso glowing luminous under the deadly ray of a vibration-gun—saw it wildly leap and seize a man, swinging him by the heels like a ninepin—then cast him off, so that his body went hurtling into the air past the roof-parapet and down into the yawning shadows of the adjacent city corridor. . . .

A mêlée of soundless death. Some of the robots were rising with their helicopters, but the guards shot them down. The roof now was littered with wrecked machinery and broken human bodies. . . . The glare of alarm-light intensified. Soundless here, but John Dyne knew that all the warning sirens in the Lower City must be screaming their alarm. . . . Then, from the side darkness, a long black aëro came darting into the light. John Dyne sucked in his breath. For an instant he thought that it was the bandits, the human controls of these berserk machines.

But it was a police car. It landed upon the roof with a crash. Human figures tumbled from it; they spread over the roof, with darting beams through the wreckage, seeking out any of the robots which still were moving. . . . There was one gigantic metal form which was the last to stay erect. It staggered the full width of the littered roof and mounted the parapet. And as though it were a human ending life, it raised its great gray arms aloft and hurled itself down into the city street.

The shadow pictures faded as Yates disconnected the box and flung it to the floor of the pit. His whole manner had altered. His triumph was gone; fear was upon him, and a frantic haste.

From the pit-floor, Sleek exulted:

“Fine lot of treasure you fellows are going to get, aren’t you? The police aren’t always asleep. You saw—”

But the elder Dyne checked him. “Easy! Don’t goad him—”

It could be fatal, with the mood which was upon Yates. His weapon swept the pit. “Yes? Well, you won’t be laughing when I turn you over to the Chief.—Move over from those controls, John Dyne. Hand me that other chain—”

John docilely obeyed. He was tense, watchful for an opening, but none came. Yates took manacles from Sleek’s equipment, and lashed John’s arms with chains and thrust him beside Sleek on the floor. He could see the motionless figure of Mekko lying where it had fallen, with the towering form of James standing like a great alumite statue above it. . . .

Through the side-panes, the night sky up the bay to the city was visible. The storm-clouds hung back above the metal towers of Manhattan. But the Jersey weather-control station was obviously attacking them now. The vague luminous glow of its beams was apparent. The clouds were shot with a weird, unnatural radiance to mark the interference. And rifts were coming.

Sleek’s car here was still some distance at sea beyond the Hook. What would Yates do?

John murmured it; and Sleek whispered back:

“The bandit control-car must have been in those clouds above the city. Yates will try and make contact with it.”

“But they don’t know he’s out here.”

“But he knows they’ll come this way.”

It seemed so. Yates was raising the car to a still higher level; he headed slowly north, then turned slowly south—waiting here.

John felt Sleek pull at his arm. “I can control Mekko. No chance yet! Too dangerous, starting anything here. . . . Look at those clouds, Johnny!”

The storm seemed spreading down the bay, coming toward them. Hidden within it was the bandit aëro, undoubtedly—coming this way, creating the dark vapor masses like a shroud around it. The storm had a fully unnatural aspect now—dark moisture-laden vapor mixed with green smoke. The electronic content was evidently in strong contrast to the natural air of the night. Halfway up the bay, a jagged fork of lightning darted down toward the towers along the Brooklyn shore; and in a moment came the peal of thunder.

John Dyne lay with arms lashed behind him. If only by some miracle he could loose the chains! What did Sleek mean, that he could control the inert Mekko? Yates still held a weapon upon them; but it was too dark here on the floor for Yates to see John Dyne as he twisted in his bonds and whispered:

“Sleek—listen! Isn’t there some way, if I twist around, that you can get me free? I can get my arms—”

“Not a chance,” Sleek murmured. “Quiet! If he sees you moving—he can kill us all with a flash. He might—if we frighten—”

Yates suddenly roared: “What the devil—” He had found that the car had all this time been displaying distress lights on the hull! With an oath he flung off the switch that darkened them.

“Who did it?” John Dyne whispered.

“Shut up!” murmured Sleek.

With all the commotion above the city, the Hook officials had not noticed these tiny lights over the sea. Yates again was waiting. A minute or so passed. The storm-area came steadily spreading seaward. The clouds were high out here now. To the north, over the ocean, the advancing edge of them was a great peak, like a strangely black thunder-head. Yates’ gaze was expectantly upon it. And as John Dyne stared, he saw from that towering cloud-peak a huge black aëro come swooping—a long, bulging, flattened hull, wingless like a surface-ship. As it came against the background of stars, he saw the rows of small, whirling-disk propellers set like flippers along the glistening black sides of its stream-lined hull.

An aëromarine! A giant thing, with a blunt, whalelike nose, a bulging middle and a fin-rudder like the tail of a killer whale strangely turned upright. The small periscope-tower set forward on its sloping deck-top could have been by its aspect a jet of spouting water. . . .

Yates had sprung into sudden action. He was lowering altitude, sending them northward and down in a swift sliding descent. His colored signal-beams flashed and waved, with an identifying signal to the oncoming bandit craft. And his signals were answered. The nose of the giant aëromarine showed a brief swaying beam. From its hull-ports smoke and vapor had been vomiting. But that suddenly stopped. It came in a swift, retarding glide; checked by its fifty or more whirling, tilting propeller disks, it hovered a few hundred feet above the calm, dark surface of the ocean as Yates dived Sleek’s tiny aëro toward it.

The contact landing needed hardly more than a moment. Sleek was shuddering; but John Dyne knew Yates’ skill as a pilot. Yates flung them a swift command.

“Lie still, you three!—James! Hold your place! Don’t move!”

John Dyne saw the great wide back of the hovering ship rising up under them, as they dived down upon it. Yates was not using the helicopters, but rushed with an old-fashioned slide-landing. . . . He missed the top of the ten-foot periscope tower by inches, flung out his skid landing-gear for this smooth, concave metal surface.

The figures of a score of men showed against the low deck-rail. . . . The aëro struck heavily; bounded from the thrust of its spring absorbers; struck again, settled and glided, retarding with back-thrust propeller-streams and grind of its brake-checkers on the metal deck.

They stopped barely short of the tail-end of the two-hundred-foot deck. Yates was on his feet, flinging open the side panels of the pit. John Dyne was standing. The upright figure of James made a move toward Yates, but the man whirled upon it.

“Stand back, I told you! —Come here, you three. Damn you—hurry!” He menaced them with his weapon. “We’ll get washed off here—they won’t wait—”

The black-garbed figures of men came running along the deck, brandishing weapons. Some one shouted:

“Who are you in there? Show your faces—make it quick!”

Yates had thrust his weapon into his belt. He leaned head and shoulders and outstretched empty arms through the opened window port. He called:

“Flash me! I’m Yates! Georg Yates. Got prisoners here. The Dynes!”

A revealing white beam sprang upon him. Voices chorused:

“Yates! It’s Yates. Come on, Yates. Quick now—”

The prisoners were tumbled to the deck. As John Dyne went over the gunwale rail of the aëro, he caught a last glimpse of the inert, prostrate figure of Mekko. The last of Mekko!

He reached the deck. Rough hands seized him. With Sleek and the elder Dyne, he was shoved forward along the deck toward where, amidships, a pressure door opened downward. Yates and the clanking robot James were close after them. . . . The wind from the upper bank of side propellers swept the deck like a gale. John Dyne saw that the huge vessel was gliding toward the ocean surface. And it seemed that off toward the Hook, at a high altitude close under the storm-clouds, an oncoming shape was visible. A police aëro? It seemed so. But it would be too late; this bandit aëromarine was diving for the sea.

The metal interior was a gloom of flickering tube-light, throbbing sounds of the vessel’s mechanism, the hurried tramp of feet and confusion of voices. The pressure-door slid closed overhead. John Dyne was standing with manacled hands, on a catwalk over a large interior room. A voice shouted:

“Guard for the shock!”

He leaned to crook an elbow over the catwalk rail. . . . The whole vessel shuddered with an impact. The outside surge of water came with a dim and distant muffled roar. Then the ship steadied, and the roar was gone as the aëromarine, nose down, slid like a plunging dolphin into the sea.

“But I don’t see Aural. Sleek, she isn’t here!”

“She may be. Take your time, Johnny. Where’s Yates? I don’t see him, either.”

“He’s over there,” whispered Robert Dyne, with a gesture. “Did you see that aëro—when we were up there on the deck? A police car after us—”

“Never get us, down here,” Sleek retorted. “Wasn’t amphibian. We’re going deep—this ship has pressure-walls. They’ll never get us. So this is where the bandits have been hiding—training their robots for crime—”

The few minutes which they had been on the ship were a chaos of disjointed revelations. Organized bandits, with this as their permanent base and hiding-place—this amphibian craft, capable of hiding in the stratosphere, illicitly creating its concealing clouds when necessary; or again plunging into the great ocean deeps, with perhaps a world-wide cruising radius! A permanent bandit crew undoubtedly manned it; but the leaders of the organization maintained on land a pseudo-respectability, executing with their trained robots a series of smaller crimes leading up to this plot against the Government vaults which had gone awry. And now the bandits, with some obscure foreign port as their destination, were escaping!

All this became evident in the first few minutes aboard the vessel. The power of money, trained organized skill, every modern device of science, was evident in the aspect of the giant craft. . . . The three prisoners were shoved half the interior length of a top level of the ship, and flung into a smaller room, where, still manacled, they stood in a group waiting to see what was to be done with them.

There seemed fully a hundred men and perhaps a dozen robots aboard the vessel. The confusion of failure and the necessity for escape were still upon the bandits. The dimly lighted room here was in a turmoil: Men coming and going; robots trying to execute incoherent orders from their masters. . . . There had several times been mention of the Chief.

“Who is he?” Sleek had whispered. “Not Benning. Not anyone we know—”

“We’ll soon find out,” said Robert Dyne. “Where is that robot James? He was supposed to guard us, but he’s gone.”

Much good it would do them to loosen their arm-chains! There was no escape from this prison-ship, which now with its pumps was sucking in the water, and with all its anti-pressure mechanisms throbbing, was leveling off at a hundred fathoms beneath the surface. . . . John had heard his father and Sleek murmuring amazement at the room through which they had been shoved when first they came aboard. But John was hardly interested, for all his thoughts were desperately upon Aural. If only she were here—not already killed back in the city! Yet why should he want her here? What fate could any of them look forward to, save death? A dozen of the bandits had pounced upon Yates, demanded why he had burdened himself and them with prisoners, and Yates had retorted:

“That is an affair for the Chief. I don’t commit murder unless it’s forced on me. Let the Chief do what he likes.”

Who was the Chief? And John’s chaotic thoughts swung to the deck overhead. Sleek’s aëro, with Mekko in it, had been left lying there. When this huge vessel submerged, the little aëro had been washed away like a drowned insect.

“I see now how they’ve been tampering with my robots,” John heard his father murmuring to Sleek. “Doing it for months—bringing them here one by one and then—”

That room through which they had passed had held familiar instruments. All the secret, intricate precision-apparatus of the Dyne factory by which the reflex motivation-scrolls of the Dyne robots were engraved—all those instruments were here. Partially dismembered Dyne robots were lying on racks in the room. Criminals in the making! A factory here for machine-made crime!

“Aural!”

John gasped it abruptly. Here in this small room where the three prisoners now stood waiting against the wall, the robot James had appeared from a connecting catwalk corridor. Its metal hands were gently pushing Aural. She stood in the doorway, unharmed—pale, frightened, but tense and grim and calm.

She heard John’s cry. Amazement, then horror swept her face as she saw him, and his father and Sleek.

“You here too? Oh—”

“Aural—”

She came running with outstretched arms. To John Dyne, as he felt them around him, came a great relief.

A stranger entered the room, a man of dominating presence. “You fellows—what are you excited over?” he demanded, of his men who were here. “We’re safe enough now—a hundred fathoms deep and no possible pursuit. What’s that girl doing here? Yates has charge of her. Where is Yates?”

“I’ll fetch him at once, Mr. Benning,” said one of the group which had followed him. The man addressed as Benning swung on the prisoners. “Surprised at all this, aren’t you? Well, look us all over while you’ve got a chance, before the Chief puts an end to you.”

No one answered him, and he turned away. John Dyne stood with Aural’s arm still around him, while she told them how, back there outside of Sleek’s office, invisible robots had flung a shadow-cloak over her, hurried her down the lift-shaft and away. She had been partially drugged; but she was conscious of an underwater river craft, controlled by robots; it had stopped somewhere, and she had been taken into an ascending helicopter—through storm-clouds—and brought here to the bandit-ship.

The bandits in the room had all been within hearing, but now it chanced that they had moved away. Sleek suddenly whispered:

“A chance for us to escape! All of us, keep together!”

John Dyne stood with pounding heart. A chance for escape! He saw, across the room, the robot James standing motionless. From a diaphragm in the machine’s head came the sound of a relayed voice. Sleek said suddenly:

“Say, Benning—some one’s calling you through the robot.”

Benning went to the machine. In the silence, John could hear the voice:

“Bring the girl and the prisoners to me in the turret.”

Benning said: “The Chief! All right—we’ll do that.”

The messenger who had been sent for Yates came back. “Yates is in the pump-room—busy—”

Benning waved the man away. He herded his prisoners forward, and the robot clanked after them. They passed from the room to an ascending corridor, and along it to a little room which was the base of the turret. It was circular, some fifteen feet in diameter. The door from the up-slanting corridor, which James now flung open, was of solid, transparent bull’s-eye glassite.

A dark-garbed, bullet-headed man was in the room, moving around its side-banks of controls with gaze upon the various dials; the illumined faces of these dials were all the light in this narrow circular apartment.

The four prisoners, the robot James, and Benning, crowded the little room.

“The Chief up above?” Benning gestured to where a tiny spiral staircase led upward ten feet through a trap in the grid-floor and into the periscope-turret.

“Yes,” said the man.

James had banged the door to the corridor, and started up the spiral. The robot’s metal fingers pulled at John so that he was second. He saw that the round turret-room was almost dark. Its side bull’s-eye panes gave a vista of the dark ocean depth moving past outside. . . .

Swift impressions. The arrivals crowded this twelve-foot circular space. At the forward bull’s-eye, gazing outward over the ship’s bow where its narrow headlight beam was thrusting into the liquid blackness as the vessel slid forward, a man was standing with hands on the steering-controls—a small, frail man: the Chief.

He turned, and Benning said: “Chief—you sent for us. Here are the prisoners. What are you—”

A little reflected glow came up through the floor-grid from the lower control-room and fell upon the Chief’s face.

He was Joc Vaine!

The recognition struck John Dyne with a startled shock of surprise; but upon it came other shocks, so swiftly that to him all were merged and blurred. So Joc Vaine was the real head of this bandit gang! His absences from the factory, which Dyne had always thought were caused by his weakness for drink, now were explained. Vaine knew every secret process of the manufacture of Dyne robots. It was he who had established this machine-crime factory, who had perfected a method of distant remote control, who had for months been secretly bringing the robots owned by his fellow human criminals here to be made into machines of crime! And this, Janna Frane had learned, and for that knowledge, she had paid with her life.

It was to John Dyne almost an instantaneous rush of comprehension. Vaine, at the steering-levers, turned to greet the newcomers.

“What does this mean?”

“Chief, didn’t you send for us?” Benning, last of them, had reached the head of the spiral.

There was a moment of confusion; gasps of astonished recognition of Vaine from Sleek and the elder Dyne; angry questions of why the prisoners were here, from Vaine, mingled with confused protestations from Benning. . . . And in the midst of it Vaine flung a sardonic gaze at his erstwhile employer.

“Well, Dyne—we meet under strange circumstances, don’t we? Benning, get them out of here—I’m busy. I’ll attend to them shortly. There’s a police aëro following over the surface—trying to get a light down to see us. . . . Get the devil out of here, all of you.”

John Dyne hardly heard any of it. Mingled and blurred with his whirling thoughts had come in those seconds a new and greater shock. The robot James, with some one evidently whispering orders to it, had shoved him against the turret-side. In the darkness he felt metal fingers behind him at the chains which bound his wrists. Aural was pressing against him, as though in fear of Vaine. Sleek stood close here. And Sleek murmured:

“I’m controlling this robot! When it cuts you loose—”

What was this? Metal fingers at the chains of his wrists? The robot’s steel pincer-finger was sliding out from the wrist, gripping the chains, cutting them!

He felt the chains come loose. He was free!

Then he saw the robot’s other arm as it came close under his face—saw the raised letters welded upon the wrist-plate:

This robot was not James, but Mekko! Complete comprehension engulfed John Dyne as he tensed, with his hands still behind him, but free. Mekko and James were of identical mold—machine-made twins. Save for the factory tag-labels and serial numbers,—and perhaps for a few dents and scars on the outer shell-plates,—their aspect was identical. Mekko’s controls had been altered by the expert Dyne, attuned only to the timbre of Sleek’s whispered voice, so that the machine was controlled only by him. Under Sleek’s surreptitious commands, Mekko had engaged in that sudden scuffle with the robot James; it was James which had fallen. Sleek had been commanding Mekko so that it acted like James; and Benning and his fellows had not known the difference!

Sleek was whispering: “Mekko will handle Vaine and Benning! You, Johnny—get the man in the room underneath us!”

Vaine was waving them all away, with his sardonic grin upon the elder Dyne. And like a bomb bursting in the close confines of the dark turret, Mekko and John Dyne sprang into action. John knocked Benning aside, gained the spiral, tumbled down it. Overhead he was conscious of Benning’s death-scream, and a roar from Sleek as with still-manacled arms he hurled himself upon Vaine. . . .

The man in the lower control-room turned only in time to go down before the blow of John’s fist on his chin. John leaped over his prostrate body and sealed the locks of the glassite corridor door. The man stirred, but John pounded him into unconsciousness, and in a few seconds was again up the spiral.

A different scene here now in those few seconds! Aural was against the wall, with hands pressed to her mouth in horror. Benning lay on the floor-grid. Sleek and Robert Dyne stood panting, straining at their bonds. And over the crouching, terror-stricken Joc Vaine, the metal form of Mekko towered like a statue.

“Hurry it!” roared Sleek. “They’ll be after us, Johnny. Up from below! You sealed that door down there?”

“Yes. —Get back, you!” John had leaped past Mekko and upon Vaine—thrust him against the wall. Vaine had not been able to draw the gun at his belt. John seized it now, held it leveled. Behind him, Sleek and his father were now freed by Mekko. Dyne was gasping:

“A matter of minutes before they’ll try and rush us here in the turret. You, Sleek, you and John can steer this ship—I can operate the lower controls—” Dyne and Vaine had both, in their younger, training days, served as mechanics on an experimental Government aëromarine of this type. Dyne added: “Head us up, John; I’ll start the pumps!”

At Sleek’s command, Mekko stood clutching Vaine—a machine-grip like a vise. Dyne hurried to the lower room. John and Sleek, with Aural pale and grim beside them, gripped the steering-levers. Through the visor-panes a dark vista of the rushing depths showed in the light of the bow-beam.

“This one, Johnny—slant us up.”

A triumph was upon John Dyne. They were in command of the ship! The bandits below virtually were prisoners, and probably as yet did not suspect what had happened. He pulled at the depth-levers; the rudders and wide-fins responded; then Sleek found a lever which controlled the thrust-angle of the multiple propellers. The vessel began ascending toward the surface in a long glide. The depth dials showed 110 fathoms—then 105, then 100. The throb of the pumps, which Dyne had reversed, was audible; water being forced out of the ballast tanks now; the ship was lightening. And the pressure-regulators of the double-shelled hull-plates were adjusting their resistance to the steadily lessening pressure of the water.

“Sleek! You see that glow up there?”

“It’s the overhead police aëro—their search-beam.”

A vague sheen seemed coming down from the overhead surface. Hardly a minute had passed since the vessel started ascending; the reversed pumps had been throbbing for thirty seconds. But it was enough to startle and puzzle the men down in the ship’s hull. The turret audiphone began peremptorily buzzing.

“Devil with it, John—”

They ignored it. They could hear Dyne accelerating the pumps. Only seventy fathoms of depth now; and in a moment or two it was fifty. The white sheen overhead was brighter now.

Dyne’s voice came up through the grid. “They can shut us off by using the manuals in the farther control-rooms! Better answer that buzzer. Put Vaine on it—make him order them—”

“Right!” exclaimed Sleek, with swift comprehension. “Rush us up, Johnny.—Come here, you, Vaine. —Mekko, let loose! Stand aside!”

“What—what do you want me to say?” gasped Vaine.

“Tell them it’s all right—you and Benning are taking us to the surface.”

Vaine shakingly lifted the receiver.

“Get your voice calm,” Sleek hissed.

Vaine gasped into the mouthpiece:

“Who—who wants me?”

“Chief! What in the devil—”

“Who—are you?” Vaine’s voice steadied. “Georg Yates?”

“Yes. In the pump-room. Why reverse—”

“I—Benning and I are taking us up—”

Sleek, hand upon the receiver, hissed: “A look around—then plunging again—”

“—To the surface to look around. Then down again. It’s all right, Yates. Stay where you are—”

As Sleek disconnected, John breathed again. That would satisfy them for a few minutes, perhaps. . . .

Twenty fathoms. Then ten. The water outside was a white glare of light now. . . . Dyne came leaping up the spiral.

“The tanks are empty! Pressure normal—one atmosphere interior here. Up with us, John.” He reached for the necessary levers for the change to air-flight. . . . John saw ahead of them the blunt bow breaking the surface—a turmoil of water lashed dazzling white in the glare. Then the periscope tower broke through.

His father shoved him away. “I’ll take us—”

The vessel heaved and shook. The water was a sloshing roar around them, as the hull-sides came up. The deck cascaded with a white torrent. The side-fins thrust out, so that the vessel glided like an aquaplane. The multiple side-propellers, as they shook free, automatically changed the angle of their blades and instantly accelerated to the whirring air-hum. The spreading fins gave an air-lift.

A moment or two, gliding, leaping, with the ground-swell of the ocean rushing past. Then the ship was free, sluggishly lifting, gathering velocity—flying.

“Did it!” murmured Dyne.

The buzzer was frantically sounding again, but no one heeded it. John Dyne, crouching by his father, saw the dark surface of the ocean dropping away beneath them. A search-beam from above bathed the turret and all the dripping deck. At the beam’s upper end—a thousand feet or so above—the gigantic blob of the police aëro showed against the background of stars.

Dyne was shouting: “Get the turret-door open, Sleek! John, show our lights! There’s the panel—it’s regulation type.”

John Dyne flashed on a distress signal. Dyne had the bandit vessel hovering now, and ascending with the helicopters. The police-ship, fully twice its size, was almost directly overhead. A warning bolt flashed down across the bow.

“Answer it, John. Ask for rescue-contact!”

John Dyne set the lights. Sleek, and Aural helping, were flinging open the turret-deck door and side bull’s-eyes. The warm, fresh air of the night rushed in. . . . The audiphone was still buzzing. From the room directly underneath the turret came a pounding—bandits imprisoned in the corridor there, trying to break the door. They would be able to do it in a moment or two.

Now John Dyne saw that the aëro above them was the largest salvage vessel of the port. Its huge magnetic crane was dangling. Against the farther star-field, other aëros were coming.

“Out to the deck, all of you!” Dyne shouted. “Get by the rail and cling! That door underneath ought to hold—”

The ship’s engines suddenly went dead. The bandits had cut off the power. The helicopters whirred to a stop.

But close over them now, the electromagnetic crane of the salvage ship came gliding down. Its spreading sidebars made contact with the metal deck; the power flashed on, gluing the bars.

“Got us!” roared Dyne. “Come on—all of you! Sleek, order Mekko to carry Vaine. Careful you don’t slip on the deck! Flash them for a ladder, John! You and Sleek help Aural!”

Perhaps the bandits smashed through the bull’s-eye door and gained the turret in time to see the little line of figures ascending the ladder up the crane-chains, and vanishing into the lower port-trap of the salvage ship. . . .

With the bandit aëro dangling helpless upon the contact-bars of the crane, the huge salvage craft headed slowly shoreward, toward where the illicit storm now was dissipating. Rain had fallen. The throbbing, vibrating beams of the Jersey weather-control station were breaking through the clouds—scattering them, so that fair weather was again coming to the busy metal city.

THE END

[The end of The Robot Rebellion by Ray Cummings]