Rane Rellis, a lanky, red-headed man with a wide-boned face, was striding down the slope towards them as they moved through the gate. "We got your alert," he said, "but as it happens, we'd already realized that something had gone wrong."

Kilby gave him a startled glance. "Somebody has been checking on you, too?"

"Not that ... at least as far as we know. Come on up to the shed. Santin's already inside the mountain." As they started along the narrow path between the rows of plants, Rellis went on, "The first responses to our inquiries came in today. One of them looked very promising. Santin flew her car to Draise immediately to inform you about it. She scanned your home as usual before calling, discovered three strange men waiting inside."

"When was this?" Halder interrupted.

"A few minutes after one o'clock. Santin checked at once at your place of work and Kilby's, learned you both were absent, deduced you were still at large and probably on your way here. She called to tell me about it. Your alert signal sounded almost before she'd finished talking."

Halder glanced at Kilby. "We seem to have escaped arrest by something like five minutes," he remarked dryly. "Were you able to bring the records with you, Rane?"

"Yes, everything. If we get clear of Orado, we can pick up almost where we left off." Rane Rellis swung the door of the cultivator shed open and followed them in, closing and locking the door behind him. They crossed quickly through the small building to an open wall portal at the far end. Beyond the portal a large, brightly lit room was visible, comfortably furnished, windowless. Between that room and the shed the portal spanned a distance of seven miles, a vital point in the organization of their escape route. If they were traced this far, the trail would end—temporarily, at least—at the ranch.

They stepped over into the room, and Rane Rellis pulled down a switch. Behind them the portal entry vanished. Back in the deserted ranch building, its mechanisms were bursting into flames, would burn fiercely for a few seconds and fuse to dead slag.

Rane said tightly, "I feel a little better now ... just a little! The Fed agents are good, but I haven't yet heard of detection devices that could drive through five hundred yards of solid rock to spot us inside a mountain." He paused as a tall girl with black hair, dark-brown eyes, came in from an adjoining room. Santin Rellis was the only one of the four who was not employing a biological disguise at the moment. In spite of the differences in their appearance, she might have been taken for Kilby's sister.

Halder told them what had occurred in Draise, concluded, "I'd believed that suspicion was more likely to center first on one of you. Particularly, of course, on Santin, working openly in Orado's Identification Center."

Santin grinned. "And, less openly, copying out identity-patterns!" she added. Her face sobered quickly again. "There's no indication of what did attract attention to you?"

Halder shook his head. "I can only think it's the microbiological work I've been doing. That, of course, would suggest that they already have an inkling of Kalechi's three-year plan to destroy the Federation."

Rane added, "And that at least one of the group already has been captured!"

"Probably."

There was silence for a moment. Santin said evenly, "That isn't a pleasant thought. Halder, everything we've learned recently at the Identification Center indicates that Rane's theory is correct ... every one of the twelve hundred members of the Kalechi group probably can be analyzed down to the same three basic identity-patterns, reshuffled in endless variation. The Federation wouldn't have to capture many of us before discovering the fact. It will then start doing exactly what we're trying to do—use it to identify the rest of the group."

Halder nodded. "I've thought of that."

"You still intend to use the Senla Starlight Cruisers to get out into space?" Rane asked.

"Kilby and I will," Halder said. "But now, of course, you two had better select one of the alternate escape routes."

"Why that?" Santin asked sharply.

Halder looked at her. "That's obvious, isn't it? There's a good chance you're still completely in the clear."

"That's possible. But it isn't a good enough reason for splitting up. We're a working team, and we should stay together, regardless of circumstances. What do you say, Rane?"

Her husband said, "I agree with you." He smiled briefly at Halder. "We'll be waiting for you on the north shore of Lake Senla ten minutes before the Starlight Cruise lifts. Now, is there anything else to discuss?"

"Not at the moment." Halder paused, dissatisfied, then went on. "All right. We still don't know just what the Federation is capable of ... one move might as easily be wrong as the other. We'll pick you up, as arranged. Kilby and I are flighthiking on to Senla, so we might as well start immediately."

They went into the second room of the underground hideout. Rane turned to the exit portal's controls, asked, "Where shall I let you out?"

"We'll take the river exit," Halder said. "Six miles from here, nine from the ranch ... that should be far enough. We'll be lost in an army of vacationers from Draise and the capital thirty seconds after we emerge."

It was dusk when Halder and Kilby turned into the crowded shore walk of the lake resort of Senla, moving unhurriedly towards a bungalow Halder had bought under another name some months before. Halder's thoughts went again over the details of the final stage of their escape from Orado. Essentially, the plan was simple. An hour from now they would slide their small star cruiser out of the bungalow's yacht stall, pick up Rane and Santin on the far shore of the lake, then join the group of thirty or so private yachts which left the resort area nightly for a two-hour flight to a casino ship stationed off the planet. A group cruise was unlikely to draw official scrutiny even tonight; and after reaching the casino, they should be able to slip on unobserved into space.

There was, however, no way of knowing with certainty that the plan ... or any other plan ... would work. It was only during the past few months that the four of them had begun to understand in detail the extent to which the vast, apparently loose complex of the Federation's worlds was actually organized. How long they had been under observation, how much the Federation suspected or knew about them—those questions were, at the moment, unanswerable. So Halder walked on in alert silence, giving his attention to anything which might be a first indication of danger in the crowds surging quietly past them along Senla's shore promenade in the summer evening. It was near the peak of the resort's season; a sense of ease and relaxation came from the people he passed, their voices seeming to blend into a single, low-pitched, friendly murmur. Well, and in time, Halder told himself, if everything went well, he and Kilby might be able to mingle undisguised, unafraid, with just such a crowd. But tonight they were hunted.

He laid his hand lightly on Kilby's arm, said, "Let's rest on that bench over there for a moment."

She smiled up at him, said, "All right," turned and led the way towards an unoccupied bench set back among the trees above the walk. They sat down, and Halder quickly slipped the watch off his wrist and removed the scanner's cover plate. The bungalow was a few hundred yards away now, on a side path which led down to the lake. It was showing no lights, but as the scanner reached into it, invisible radiation flooded the dark rooms and hallway, disclosing them to the instrument's inspection. For two or three minutes, Halder studied the bungalow's interior carefully; then he shifted the view to the grounds outside, finally to the yacht stall and the little star cruiser. Twice Kilby touched him warningly as somebody appeared about to approach the bench, and Halder put down his hand. But the strangers went by without pausing.

At last, he replaced the instrument on his wrist. He had discovered no signs of intrusion in the bungalow; and, at any rate, it was clear that no one was waiting there now, either in the little house itself or in the immediate vicinity. He stood up, and put out his hand to assist Kilby to her feet.

"We'll go on," he said.

A few minutes later, they came along a narrow garden path to the bungalow's dark side entrance. There was to be no indication tonight that the bungalow had occupants. Halder unlocked the door quietly, and after Kilby had slipped inside, he stepped in behind her and secured the door.

For an instant, as they moved along the short, lightless passage to the front rooms, a curious sensation touched Halder—a terrifying conviction that some undefinable thing had just gone wrong. And with that, his whole body was suddenly rigid, every muscle locking in mid-motion. He felt momentum topple him slowly forwards; then he was no longer falling but stopped, tilted off-balance at a grotesque angle, suspended in a web of forces he could not feel. Not the slightest sound had come from Kilby, invisible in the blackness ahead of him.

Halder threw all his will and strength into the effort to force motion back into his body. Instead, a wave of cold numbness washed slowly up through him. It welled into his brain, and for a time all thought and sensation ended.

His first new awareness was a feeling of being asleep and not knowing how to wake up. There was no disturbance associated with it. All about was darkness, complete and quiet.

With curious deliberation, Halder's senses now began bringing other things to his attention. He was seated, half reclining, in a deep and comfortable chair, his back against it. He seemed unable to move. His arms were secured in some manner to the chair's armrests; but, beyond that, he also found it impossible to lift his body forwards or, he discovered next, to turn his head in any direction. He was breathing normally, and he could open and shut his eyes and glance about in unchanging darkness. But that was all.

Still with a dreamlike lack of concern, Halder began to ask himself what had happened; and in that instant, with a rush of hot terror, his memory opened out. They had been trapped ... some undetectable trick of Federation science had waited for them in the bungalow at Lake Senla. He had been taken somewhere else.

What had they done with Kilby?

Immediately, almost as if in answer to his question, the darkness seemed to lighten. But the process was gradual; seconds passed before Halder gained the impression of a very large room of indefinite proportions. Twenty feet away was the rim of a black, circular depression in the flooring. At first, his chair seemed the only piece of furnishing here; then, as the area continued to brighten, Halder became aware of several objects at some distance on his right.

For an instant, he strained violently to turn his head towards them. That was still impossible, but the objects were there, near the edge of his vision. Again the great room grew lighter, and for seconds Halder could distinguish three armchairs like his own, spaced perhaps twenty feet apart along the rim of the central pit. Each chair had an occupant; in the nearest was Kilby, restored to her natural appearance, motionless, pale face turned forwards, eyes open. Suddenly the light vanished.

Halder sat shocked, realizing he had tried to speak to Kilby and that no sound had come from his throat. Neither speech nor motion was allowed them here. But he didn't doubt that Kilby was awake, or that Santin and Rane Rellis were in the farther chairs, though he hadn't seen either of them clearly. Their captors had given them a brief glimpse of one another, perhaps to let them know all had been caught. Then, as the light disappeared, Halder's glance had shifted for an instant to his right hand lying on the armrest—long enough to see that the dark tinge was gone from his skin, as it was from Kilby's, that he, too, had been deprived of the organisms which disguised him.

And that, his studies in Draise had showed clearly, was something the Federation's science would be a century away from knowing how to do unless it learned about Kalechi's deadly skills.

Once more, it was almost as if the thought were being given an answer. In the darkness of the room a bright image appeared, three-dimensional, not quite a sphere in form, tiger-striped in orange and black, balanced on a broad, bifurcated swimming tail. Stalked eyes protruded from the top of the sphere; their slit pupils seemed to be staring directly at Halder. Down both sides ran a row of ropy arms.

Simultaneously with the appearance of this projection, a man's voice began to speak, not loudly but distinctly. Dreamlike again, the voice seemed to have no specific source, as if it were coming from every direction at once; and a numbing conviction arose in Halder that their minds were being destroyed in this room, that a methodical dissecting process had begun which would continue move by move and hour by hour until the Federation's scientists were satisfied that no further scraps of information could be drained from the prisoners. The investigation might be completely impersonal; but the fact that they were being ignored here as sentient beings, were not permitted to argue their case or offer an explanation, seemed more chilling than deliberate brutality. And yet, Halder told himself, he couldn't really blame anyone for the situation they were in. The Kalechi group represented an urgent and terrible threat. The Federation could not afford to make any mistakes in dealing with it.

"This image," the voice was saying, "represents a Great Satog, the oxygen-breathing, water-dwelling native of the world of Kalechi. There are numerous type-variations of the species. Shown here is the dominant form. It is highly intelligent; approximately a third of a Satog's body space is occupied by its brain.

"Kalechi's civilization is based on an understanding of biological processes and the means of their manipulation which is well in advance of our own. This specialized interest appears to have developed from the Satogs' genetic instability, a factor which they have learned to control and to use to their advantage. At present, they have established themselves on at least a dozen other worlds, existing on each in a modified form which is completely adapted to the new environment.

"Our occasional contacts with Kalechi and its colonies during the past two centuries have been superficially friendly, but it appears now that the Great Satogs have regarded our technological and numerical superiority with alarm and have cast about for a method to destroy the Federation without risk to themselves. A weapon was on hand—their great skill and experience in altering genetic patterns in established life forms to produce desired changes. They devised the plan of distributing Kalechi agents secretly throughout the Federation. These were to develop and store specific strains of primitive organisms which, at an indicated later date, would sweep our major worlds simultaneously with an unparalleled storm of plagues.

"The most audacious part of the Kalechi scheme follows. Ninety-two years ago, a Federation survey ship disappeared in that sector of the galaxy. Aboard it was a man named Ohl Cantrall, an outstanding scientist of the period. We know now that this ship was captured by the Great Satogs, and that Cantrall, his staff, and his crew, were subjected to extensive experimentation by them, and eventually were killed.

"The experimentation had been designed to provide Kalechi's master-biologists with models towards which to work. They proposed to utilize the high mutability of their species to develop a Satog type that would be the exact physical counterpart of a human being and could live undetected on our worlds for the several years required to prepare for the attack. They were amazingly successful. Each group of cells in the long series which began moving towards an approximation of the human pattern was developed only far enough to initiate the greatest favorable shift possible at that point in its genetic structure. Cell generations may have followed each other within hours in this manner, for over six decades.

"The goal of the experiment, the last generation issued in Kalechi's laboratories, were Satog copies of embryonic human beings. This stage was comprised of approximately twelve hundred individuals who were now permitted to mature and were schooled individually in complete isolation by Satog teachers. They were indoctrinated with their purpose in life ... the destruction of our populations ... and trained fully in the manner of accomplishing it.

"Eventually, each was shipped to a Federation world. Cover identities as obscure Federation citizens with backgrounds and records had been prepared. The final instructions given these agents were simple. They were to do nothing to draw attention to themselves, make no attempt to contact one another. They were to create their stocks of lethal organisms, provide methods of distribution and, on a selected day, three Federation years away, release the floods of death."

The voice paused briefly, went on. "It is a sobering reflection that this plan—an attack by a comparatively minor race with one specialized skill on the greatest human civilization in history—might very well have been appallingly successful. But the Great Satogs failed, in part because of the very perfection of their work.

"From the human beings on board Ohl Cantrall's captured survey ship the Satog scientists selected Cantrall himself and two female technicians on his staff as the models to be followed in developing Kalechi's pseudohumanity. In the twelve hundred members of the group sent to the Federation ninety years later, these three identity-patterns are recognizable. They appear in varying degrees of combination, but an occasional individual will show only one or the other of the three patterns involved.

"Ohl Cantrall was regarded as a great man in his time, and his identification pattern is on record. That was the detail which first revealed the plot. When three duplicates of that particular pattern—and a considerable number of approximate duplicates—turned up simultaneously in identification banks at widely separated points in the Federation, it aroused more than scientific curiosity. Our security system has learned to look with suspicion on apparent miracles. The unsuspecting 'Cantralls' were located and apprehended at once; the threat to the Federation was disclosed; and an intensive though unpublicized search for the scattered group of Kalechi agents began immediately...."

The voice paused again.

The Satog image above the pit vanished. A clear light sprang up in the big room. Simultaneously, Halder felt the nightmare immobility draining from him and the sensation of dreamlike unreality fade from his mind. He turned to the right, found Kilby's eyes already on him, saw the Rellis couple sitting beyond her ... Rane, no longer disguised, looking like a mirror image of Halder.

They were still fastened to their chairs. Halder's gaze shifted back quickly to the center of the room. Where the pit had been, the flooring was now level, carrying a massive, polished table. Behind the table sat a heavily built, white-haired man with a strong face, harsh mouth, in the formal black and gold robes of a Councilman of the Federation.

"I am Councilman Mavig." The voice was the one that had spoken in the dark; it came now from the man at the table. "I am in charge of the operation against the Kalechi agents, and it is my duty to inform them, after their arrest and examination, of the disposition that must be made of them."

He hesitated, twisting his mouth thoughtfully, almost as if unwilling to continue. "You four have been thoroughly examined," he stated at last. "Most of the work has been done while you were still unconscious. A final check of your emotional reactions was being made throughout the stress situation just ended, in which you listened to a replay of a report on the Kalechi matter. That part is now concluded."

Mavig paused, scowled, cleared his throat. "I find," he went on, "that some aspects of this affair still strain my credulity! More than half of your group have been captured by now; the remainder are at large but under observation. The danger is past. The activities of the Great Satogs of Kalechi will receive our very close scrutiny for generations to come. They shall be given no opportunity to repeat such a trick; nor—after they have been made aware of the measures we are preparing against them—will they feel the slightest inclination to try it.

"Now, as to yourselves. After we had tracked down the first dozen or so of you, a startling pattern began to emerge. You were not following Kalechi's careful instructions. In one way and another—in often very ingenious ways—you were attempting primarily to establish contact with one another. When captured and examined while unconscious by the various interrogation instruments of our psychologists you told us your reasons for doing this."

Councilman Mavig shook his head. "The interrogation machines are supposed to be infallible," he remarked. "Possibly they are. But I am not a psychologist, and for a long time I refused to accept the reports they returned. But still ..."

He sighed. "Well, as to what is to happen with you. You will be sent to join the previously arrested members of your group, and will remain with them until the last of you is in our hands, has been examined, and ..."

Mavig paused again.

"You see, we can accuse you of no crime!" he said irritably. "As individuals and as a group, your intention from the beginning has been to prevent the crime against the Federation from being committed. The Great Satogs simply did too good a job. You have been given the most searching physical examinations possible. They show uniformly that your genetic pattern is stable, and that in no detail can it be distinguished from a wholly human one of high order.

"You appreciate, I imagine, where that leaves the Federation! When imitation is carried to the point of identity ..." Federation Councilman Mavig shook his head once more, concluded, "It is utterly absurd, in direct contradiction to everything we have understood to date! You've regarded yourselves as human beings, and believed that your place was among us. And we can only agree."