"I don't know, Park. Look at the left-hand side, there. See it? There's something different there, a dark spot."

The image on the screen was still growing steadily larger and clearer as theship neared rendezvous. It was difficult for Wolf and Green to suppress their impatience as the asteroid's milky surface slowly became more visible. Soon it was obvious that the dark spot was more than a patch of different reflectance, and there were other faint mottlings and markings on the smooth surface, tinged with a cloudy green.

"It's some kind of a pit, Bey." Green hunched closer to the screen. "Maybe a tunnel. See where it angles down into the surface? I don't remember anything like that in any of the descriptions of Pearl."

Bey was nodding his head in satisfaction.

"It's not a natural formation. Somebody's been doing heavy engineering there.

See how sharp those edges are? I'll bet that was cut with a big materials laser. Park, there's no way that Capman-or anybody else-could have done all that without a lot of a.s.sistance and equipment. You know what that means?

Somebody in the USF has been helping him-and whoever it was has lots of resources to play with."

The computer interrupted his final words with a soft whistle. The orbit match was complete. They stared hard at the nearby asteroid. From a distance of one kilometer, Pearl filled a quarter of the sky. The whole surface shone with a pale, satiny gleam. It was smooth and unbroken, without any irregularity except for the exact, circular hole thirty meters in diameter that showed its black disk near the left side of the image.

They studied it in silence for a few minutes. Finally Bey moved over to the computer console.

"It's no good, Park," he said. "We can't learn much from here. There's nothing to see on the surface. We have to get a look at the inside. I'll bet that tunnel runs right through to the interior. We'll need suits."

"Both of us?"

"Unless you're willing to stay behind here. I know I didn't come all this way to watch. The computer has everything under control on the ship. I think it's safe enough to go in close and jump the gap wearing our suits. Take us in to fifty meters, and let's go."

The two men, fully suited, drifted across from ship to surface. The gravity of Pearl was too small to be noticed. They hovered a few feet from the planetoid and looked at it more closely. It was clear why Pearl shone so softly. Through the many millennia since Loge's explosion, the impact of micrometeorites had pitted the surface, to develop a matte, frosted coaling that caught and diffused the light from the distant Sun. Pure white alternated with greenish clouds in a patchwork over the sphere. The two men drifted slowly toward the tunnel. Near the edge, Wolf shone a hand torch downward. Deep channels had been scored in the smooth gla.s.s by heavy equipment. The hole narrowed as it descended, ending about fifteen meters down in a smooth plate of black metal.

Wolf whistled to himself, the sound thin and eerie over the suit radios. "That disposes of the idea that n.o.body's allowed to land on Pearl. Why would anybody put in an air lock down there if it's just an empty sh.e.l.l?" He looked down the steep-sided hole. "Ready to go down, Park? All we need now is the White Rabbit."

They floated together downward to the big portal, untagged the outer door, and went inside. Green took hold of the port, then hesitated for a moment.

"Should I close it, Bey? We don't know what we may be getting into. There could be anything inside."

"I don't see that we have much choice. Either we go in or we go back. I'm expecting to find Capman behind the door and John La.r.s.en with him. If you want to stand guard outside, that's fine-but I'm going in."

Green did not answer, but he pulled the outer door firmly shut and dogged it with the clamps. There was at once a hissing of air.

"Don't a.s.sume that it will be breathable," warned Wolf as the inner door swung open. "John should be here, and the atmosphere may be his idea of nice fresh air."

Green snorted. "Bey, give a USF man some credit. Anybody who grew up off-Earth would no more try and breathe untested air than want to live back down onEarth and breathe your soup. Look at the second display panel in the helmet inset. It's registering 6-S. That means it's safe to breathe and a little less than half Earth-normal for pressure. All the same, I'm going to keep my suit closed. I suggest you should do the same."

The inner door was slowly irising open. A pale green light filtered into the lock from the interior of the planetoid. With the port open to its full thirty-meter diameter, the whole of the inside of Pearl became visible. In complete silence the two men drifted forward together, looking about them.

The inner wall of Pearl had a smooth, shiny finish that had been missing on the exterior. No meteorites had marred its perfection. The inner surface was a perfect globe, a little more than a mile in diameter. In the center of the vast, arching chamber, tethered to the wall by long, glittering struts and cables, hung two great metal structures. The nearer was itself another bright sphere of steel or aluminum. Bey, eyeing it thoughtfully, wondered at the source of the materials that had been used in its construction. Certainly they had not come from Pearl itself. Considering the energy needed to transport materials from the main system, it seemed certain that the ball must have been built from metals mined on one of the sister asteroids of the Egyptian Cl.u.s.ter. Bey estimated that the sphere was a hundred meters across. A long tubular cable led from the port where they had entered to another lock on the sphere's smooth face.

The second structure could only be a ship. That made no sense. Bey looked around him again. There appeared to be no way that the vessel, forty meters across at the widest point, could have reached the interior of Pearl-or, once there, could ever leave it. His eyes followed the guide cables that led from the ship to a slightly darker section of the inner wall, directly opposite to the point where they had entered. It had to be a concealed exit. Other cables, running to empty areas in the interior, hinted at the sometime presence of other ships, moored to the inner surface in the same way.

The surface of Pearl, with its wall of translucent gla.s.s, provided an efficient conversion of incident solar radiation. The suit thermometers indicated an ambient temperature quite comfortable for human habitation. The inside was lit with the faint sunlight that had been transmitted through the outer walls and suffused about the interior. There were no shadows except those thrown by the torches that Wolf and Green were carrying.

At first Pearl seemed completely silent, a dead world. As their ears adjusted, Wolf and Green became aware of a deep, m.u.f.fled pulsing, felt more than heard, filling the interior. It came from the metal sphere at the center of the asteroid, regular and slow, like the working of air or nutrient circulators or the beating of a vast heart. Nowhere through the great s.p.a.ce of the central bubble was there any other sound or sign of life.

Park Green finally broke the spell. "I'm beginning to think I don't know anything at all about the USF. There's no way this place can exist. That ship up there must be unregistered, and if Capman came here in it I can't even guess where he could have started out from. Not Tycho, that's for sure."

Wolf grunted his agreement. His instincts told him that something was very wrong. He had come to Pearl convinced that he would find Capman and La.r.s.en there. If that were true, surely there should be some sign of their presence.

He looked again at the metal sphere ahead of them. Without speaking both men moved to the great hollow cable that led there from the entry port.

As they started along it, the sheer size of Pearl came home to Bey. The far wall looked close at hand, but the vaulted interior of the asteroid could easily have contained tens of millions of Earth dwelling units. They progressed along the cable until their entry lock behind them had shrunk to a small black dot. They both felt more comfortable when they had finally reached the sphere and entered the lock on its shining face.

The first rooms were clearly living quarters. The furnishings were simple, but there was expensive automated equipment to handle all routine ch.o.r.es. Bey, seeing the food delivery system, realized how long it had been since they had eaten. He looked at Green."What do you think, Park? a.s.suming that's in good working order, are you ready to risk the air in here?"

Green was looking hungrily at the dials of the robochef. He nodded. "I think we're safe enough, as long as we don't go through any air locks. This area is a standard USF automat life support, with a few VIP luxuries thrown in. Take a good look at that menu. I'll bet you don't eat Uke that back on poor old Earth."

Unsuited, they felt a good deal of the tension evaporate. There was still no sign of life, and by the time they were ready to continue their exploration, Bey had become convinced that the whole sphere was uninhabited. After the living quarters came three rooms crammed with monitors and control consoles, exactly like the general control room for a form-change lab-similar, and yet dissimilar. It was bigger than anything Bey had ever seen, bigger even than the research center facility at BEC.

"The tanks should be behind that wall," he said, explaining to Park Green what they had found. "But I don't think we'll find John there. Somewhere, I missed the point. I was sure I was right, then-"

He shrugged and looked about him. Four years earlier he had thought he knew what Capman was doing-only to find that he had been outthought every step of the way. It could happen twice. Capman had expected him to unravel the skein that led to Pearl. If necessary, John La.r.s.en could provide a little prompting, since it was clear that he had been in constant communication with Capman ever since the change to a Logian form. Once he knew that Bey was on the way, La.r.s.en had promptly disappeared.

It all sounded so logical-but so unlikely. Bey wasn't sure that he could explain to Park Green just how they had been guided here like a couple of puppets.

While Wolf stood there in silence, Green had been looking closely at the control panel.

"Bey, I know I'm no expert on this stuff, but look at the readouts. They all seem to be from one tank. Could all these be from one form-change station?"

Wolf came forward also. He studied the panels for a few seconds, his face puzzled. "It looks like it, I admit. But there are far too many monitors for one subject. There have to be three hundred of them. I've never seen anything nearly as complicated for one experiment. I wonder if it could be ... "

He stood, unwilling to state his own belief.

"You and your companion are quite correct, Mr. Wolf," said the speaker grille above the console. "This is indeed all one experiment."

CHAPTER 21.

"Capman?" Wolf swung around swiftly to face the grille.

"No, I am not Robert Capman. I am an old friend of his. In fact"-there was a hint of amus.e.m.e.nt in the light, musical tone-"I could fairly say that I'm a very old friend. Welcome to Pearl. I have heard a great deal about you from both Robert Capman and John La.r.s.en."

Green was looking around him in confusion. "Where are you? The only way out of here looks as though it leads to the tanks."

"Correct. I am in the tank area. It is quite safe for you to proceed through at the moment. I am maintaining the atmosphere at the same level as in the rest of Pearl."

"Should we come through?" asked Wolf.

"Come through by all means, but be ready for a shock. You perhaps consider that you are past surprise, Mr. Wolf, but I am not sure that the same is true for Mr. Green."

"But where are Capman and La.r.s.en?"

"Far from here. Mr. Wolf, the conversion of John La.r.s.en to an alien form was completely unexpected. It added a new dimension to an activity that was already vastly complex. But it also provided great benefits. Part of theexplanation of our activities is not mine to give, and you must hear it from Capman. Part, however, I can tell you. Come through into the tank."

Wolf and Green looked at each other, and finally Bey shrugged. "I'll go first.

I don't think there will be any danger. I don't know what we're going to see, but I've had a close look at most things in the years with Form Control."

The chamber that they entered was enormous. It occupied at least half of the whole metal sphere. Bey looked around him in vain for the familiar tank fittings. At first he could see nothing that he recognized. Then, suddenly, what he was looking at made sense. He gasped. It was a tank, but the proportions on the service modules were unbelievable. Nutrient feeds and circulators were ma.s.sive pipes, each two meters in diameter, and the neural connectors were heavy cl.u.s.ters of wave guides and thick fiber-optic bundles.

Bey looked around for the origin of the voice, but it was all a complex series of interlocking vats, each one large enough to hold several men. He could see nothing to tell him where to focus his attention.

"Where are you?" he said at last. "Are you in one of the vats?"

"Yes and no." The voice now seemed to come from all sides, and again there was a hint of detached amus.e.m.e.nt in the tone. "I am in all the vats, Mr. Wolf.

This experiment has been going on here for a long time. My total body ma.s.s must be well above a hundred tons by now, but of course it is distributed over a large volume."

Green, mouth gaping open, was goggling around him like a startled frog. Bey felt that his own expression must be much the same. "Are you human, or some kind of biological computer?" he said at last.

"A good question indeed, and one that has exercised my mind more than a little over the past few years. I am tempted to say simply, yes."

"You're both? But then where is your brain located?" asked Green.

"The organic part is in the large tank straight in front of you, at the rear of the chamber. You can pick it out easily by the number of sensor leads that feed into it. The inorganic part-the computer-is in a distributed network extending through most of the sphere. As you will gather, Robert Capman has shown that the idea of man-machine interaction can go a good deal further than a computational implant."

"But how do you ... " Wolf paused. His mind was seeing a hundred new possibilities and a hundred new problems to go along with them.

"If there is no one else here," he went on, "how can you get the nutrient supply that you need? And how can you ever change back? I a.s.sume that you began as a human form." Another disturbing possibility suddenly suggested itself. "How did you get to be like this? Was it voluntary, or were you forced to take this form?"

"Questions, questions." The voice sighed. "Some of them, I have promised not to answer. Their replies, if you want them, must come from Robert Capman himself. One thing I can guarantee, a reverse form-change would be very difficult. On the other hand, by the time I expect to be interested in such a thing, I feel sure that the capability will be well established-perhaps even forgotten. Enough of that. If you would please turn around ... "

The voice, for all its bizarre origin, sounded cheerful and rational, even amused. As Wolf and Green turned to look behind them, a screen flashed into color on the nearer wall of the tank.

"How do I obtain my nutrients, you ask. Very efficiently. My whole life-support system is completely self-contained. Look at the screen and let me take you on a brief tour of Pearl. We are leaving now and heading out to the inner surface."

The screen showed the output of a mobile vidicon that was moving steadily out along one of the connecting cables that led to the inside wall of the asteroid. Seen close up, it was clear that many of the cables were much more than simple supporting members for the sphere. They included tubes, communication guides, and flexible connection points onto which other cables could easily be joined. As the vidicon came closer to the wall, it was again obvious that the image on the screen showed something more complex than thesmooth, gla.s.sy surface that appeared from a distance. Some patches were lighter than the background and transmitted a light distinctly greener in color.

"Algal tanks!" said Park Green suddenly. "Just like the ones in the Liberation Colonies. But these must be cut into the surface of Pearl. See how green the light looks."

"Quite right," said the disembodied voice. "You can see what a great convenience it is to have an asteroid that was almost designed by nature for our purpose. The algae are the source of both my air and my nutrients. We are one closed system, including all the circulation equipment. The thermal gradients do all the work. It is no longer necessary for Capman-or anyone else-to be here to provide services to me. That control console you saw outside is no longer needed here. In fact, I control it myself, through the computer network. The whole of Pearl is a single self-contained environment."

Long experience had inured Bey to just about every conceivable form, but Park Green was much less comfortable with what he was seeing and hearing. He seemed horrified by the implications of the conversation.

"Capman did this to you, did he?" he finally burst out. "Surely he knew what he was creating. You can't move from here, you're tied to Pearl, and you can't do a reverse form-change. You don't even have anyone here to talk to or relate to. You, whatever you once were, don't you see what he's done to you? Didn't you know he's a murderer? How can you stand it?"

"Still more questions." For the first time, the voice sounded irritated. "My name, for what it matters, is Mestel. I need pity from no one. For your other remarks, perhaps I should point out that you are completely captive in your body, at least as much as I am in mine. Who is not? And I possess a degree of control over my own movement, care, and protection that you certainly are lacking. How can you stand it?"

"Movement?" Bey picked up on the word. "You mean vicarious movement, through the remote sensors?"

"No-though I have that too. I mean physical movement, as a whole. Wait and see, Mr. Wolf. I admit that I am bound to Pearl for an indefinite period. But why should that be considered a disadvantage? If I can believe the newscasts that I have picked up in the past few weeks, Pearl may soon be the only place left with a decent level of civilization. Or has old Laszlo become even more of a pessimist than usual?

"Perhaps that is enough talk." Mestel's voice became sharper in tone. "I suppose that I do miss the opportunity for conversations without light-time delays. Now I have another duty to perform. Your arrival here was expected, but it was not clear when you might come or how many of you there would be. I thought you would arrive alone, Mr. Wolf. Robert Capman believed that Mr.

Green would arrive also, and John La.r.s.en insisted on it." A curious amplified noise came from the speaker. Mestel had sniffed. "Whatever it is that makes up the Logian form, there is formidable intellect there. With all the computer a.s.sistance that is built into me, I expect to outthink anyone except Capman.

Others abide the question, but he is outside normal experience. Now it seems that La.r.s.en can think rings around both of us."

"That's my feeling, too," said Bey. "I knew John very well before the change, and it's not being unkind to say that he was no great intellect. Now he's something special. Robert Capman has always been something special."

"I know you think that. Now let me ask a question that you alone can answer.

You have pursued Capman steadily since your first meeting, down the nights and down the days, down the arches of the years. If you wish to pursue him further, there will now be a significant risk to you. You will also be away from Earth for many months. Do you want to proceed on those terms?"

"Wait a minute," said Green. "What about me? I've been in on this from the beginning, at least as far as the Logian forms are concerned. I'm not going to-be left out of things now."

"You will not be left out, Mr. Green. You and I, for our sins, will be embarking on a different mission. It is a crucial and a demanding one, but itdoes not include a meeting with Robert Capman. That encounter is not necessary for us. But there are reasons why Behrooz Wolf needs one more meeting with La.r.s.en and Capman."

Wolf was listening very closely. He was intrigued by the intonation in Mestel's voice and by the slightly old-fashioned and formal manner of phrasing and address. He looked around him again at the tank. Apart from the sheer size, it showed an individual taste in the layout, a little different from the standard arrangement.

"Mestel," he said at last. "Is the layout of this place your work, or did Capman do it for you?"

"Capman and a work crew arranged for the physical labor. That was before I had full control of the remote handling equipment, so I still needed help. Now I could do the whole thing with my waldos. I did all the specifications, though-Robert never did care at all what his surroundings looked like; he lived inside his head."

Wolf was nodding in satisfaction. "Then I'd like to ask you a couple more questions. How old are you, and are you male or female?"

Green looked at Wolf in astonishment. But Mestel was laughing heartily, a musical gale of sound that swept out of a hundred speakers inside the great tank.

"Male or female? Come, Mr. Wolf, is it not apparent that the question is now purely academic? I presume you mean, was my original form male or female? Full marks. My name is Betha Mestel, and I was for many years a female-but never, I'm glad to say, a lady. Robert Capman told me that you have an unmatched talent for reading through an exterior form. I see he did not exaggerate. Can you go further? On the basis of what I have already said, would you like to attempt further deduction?"

Bey was nodding thoughtfully, dark eyes hooded by the half-closed lids. "Betha is not a name much used now. It had a big vogue a hundred and twenty years ago, and you said you are an old friend of Capman." He paused. "I think I am beginning to see a whole lot of things that should have been obvious to me a long time ago. Is it possible that you-"

"Never, as they said in the old days, ask a woman her age." Beneath the flirtatious tone of Betha Mestel's voice there was an undercurrent that was anything but casual. "As you surmise, the answer would take us far a field. I must return to my question and ask again: Mr. Wolf, are you willing to take the risk that a meeting with Robert Capman would entail?"

"Definitely." Wolf's voice was firm, his resolution increased by the implications of Betha Mestel's words. "How do I get to him?"

Wolf paused. The far side of the room was suddenly indistinct, a blur of color in front of his eyes.

"I will get you to him. Mr. Green and I will not go with you; we have our own duties to perform back in the Inner System." The voice was fainter, farther away. "Let me apologize to you for what is about to happen. There are good reasons for this, also. Relax, both of you."

Neither Park Green nor Bey Wolf had heard Mestel's final sentence. Two of the handling waldos came forward and gently carried the two unconscious forms back toward the control room.

One hundred million kilometers above the ecliptic, there is an isolation that is more complete than anything found in the plane of the planets. There were no observers to watch Pearl as the asteroid moved steadily on its three-year circuit around the Sun. The nearest inhabited object was Horus, with its fifty-man mining outpost. That group was far too busy to spend any of their time heavens-watching. In any case, at thirty million kilometers distance, Pearl was at the resolution limit of their best telescopes.

No one saw the great lock in the side of Pearl iris open, and the ship emerge from it like a small, bright minnow darting from the shelter of a hollow rock.

The ship fell freely for a while, until it was a safe distance from the asteroid. Then the fusion drive went on. The ship began to move out and down, dipping toward the ecliptic on a trajectory that headed farther from the Sun.The single pa.s.senger knew nothing of the motion. He was coc.o.o.ned deep within the form-change tank at the ship's center.

Soon afterward, the mechanical handlers emerged from Pearl's smaller lock.