But after a while, overwhelmed by the sheer number of dead, Clavain had allowed the exact details of Setterholm"s death to slip from his mind. He was hardly unique anyway: just one more example of the way most of them had died; not by suicide or violence but through carelessness, recklessness or just plain stupidity. Basic safety procedures-like not wandering into a creva.s.se zone without the right equipment-had been forgotten or ignored. Machines had been used improperly. Drugs had been administered incorrectly. Sometimes the victim had taken only themselves to the grave, but in other cases the death-toll had been much higher. And it had all happened swiftly.

Galiana talked about it as if it was some kind of psychosis, while the other Conjoiners speculated about some kind of emergent neural condition, buried in the gene-pool of the entire colony, lurking for years until it was activated by an environmental trigger.

Clavain, while not discounting his friends" theories, could not help but think of the worms. They were everywhere, after all, and the Americans had certainly been interested in them-Setterholm especially.

Clavain himself had pressed his faceplate against the ice and seen that the worms reached down to the depth where the man had died. Their fine burrowing trails scratched into the vertical ice walls like the branchings of a river delta; the dark nodes of breeding tangles at the intersections of the larger tunnels.

The tiny black worms had infested the glacier completely, and this would only be one distinct colony out of the millions that existed all over Diadem"s frozen regions. The worm bioma.s.s in this one colony must have been several dozen tons at the very least. Had the Americans" studies of the worms unleashed something which shattered the mind, turning them all into stumbling fools?

He sensed Galiana"s quiet presence at the back of his thoughts, where she had not been a moment earlier.

"Nevil," she said. "We"re ready to leave again."

"You"re done with the ruin already?"

"It isn"t very interesting-just a few equipment shacks. There are still some remains to the north we have to look over, and it"d be good to get there before nightfall."

"But I"ve only been gone half an hour or..."

"Two hours, Nevil."

He checked his wrist display unbelievingly, but Galiana was right: he had been out alone on the glacier for all that time. Time away from the others always seemed to fly by, like sleep to an exhausted man.

Perhaps the a.n.a.logy was accurate, at that: sleep was when the mammalian brain took a rest from the business of processing the external universe, allowing the acc.u.mulated experience of the day to filter down into long-term memory; collating useful memories and discarding what did not need to be remembered. And for Clavain-who still needed normal sleep-these periods away from the others were when his mind took a rest from the business of engaging in frantic neural communion with the other Conjoiners. He could almost feel his neurones breathing a vast collective groan of relief, now that all they had to do was process the thoughts of a single mind.

Two hours was nowhere near enough.

"I"ll be back shortly," Clavain said. "I just want to pick up some more worm samples, then I"ll be on my way."

"You"ve picked up hundreds of the d.a.m.ned things already, Nevil, and they"re all the same, give or take a few trivial differences." "I know. But it can"t hurt to indulge an old man"s irrational fancies, can it?"

As if to justify himself, he knelt down and began scooping surface ice into a small sample container.

The leech-sized worms riddled the ice so thoroughly that he was bound to have picked up a few individuals in this sample, even though he would not know for sure until he got back to the shuttle"s lab. If he was lucky, the sample might even hold a breeding tangle; a knot of several dozen worms engaged in a slow, complicated orgy of cannibalism and s.e.x. There, he would complete the same comprehensive scans he had run on all the other worms he had picked up, trying to guess just why the Americans had devoted so much effort to studying them. And doubtless he would get exactly the same results he had found previously. The worms never changed; there was no astonishing mutation buried in every hundredth or even thousandth specimen; no stunning biochemical trickery going on inside them. They secreted a few simple enzymes and they ate pollen grains and ice-bound algae and they wriggled their way through cracks in the ice, and when they met other worms they obeyed the brainless rules of life, death and procreation.

That was all they did.

Galiana, in other words, was right: the worms had simply become an excuse for him to spend time away from the rest of the Conjoiners.

Before any of them had left Earth"s solar system, Clavain had been a soldier, fighting on the side of the faction which directly opposed Galiana"s experiments in mind-augmentation. He had fought against her Conjoiners on Mars, and she had taken him prisoner at the height of the war. Later-when he was older, and when an uneasy truce looked like it was at the point of collapsing-Clavain had gone back to Mars with the intention of reasoning with Galiana. It was during that peace mission that he realized-for the sake of his conscience-that he had to defect and fight alongside his old enemy, even though that meant accepting Galiana"s machines into his head.

Later, along with Galiana, Felka and their allies, Clavain had escaped from the system in a prototype starship, the Sandra Voi. Clavain"s old side had done their best to stop the ship leaving, but they had failed, and the Sandra Voi had safely reached interstellar s.p.a.ce. Galiana"s intention had been to explore a number of solar systems within a dozen or so light years of Earth, until she found a world that her party could colonize without the risk of persecution.

Diadem had been their first port of call.

At the beginning of the expedition, a month ago, it had been much easier to justify these excursions.

Even some of the true Conjoined had been drawn by a primal human urge to walk out into the wilderness, surrounding themselves with kilometers of beautifully tinted, elegantly fractured, unthinking ice. It was good to be somewhere quiet and pristine, after the war-torn solar system that they had left behind.

Diadem was an earthlike planet orbiting the star Ross 248. It had oceans, icecaps, plate tectonics and signs of reasonably advanced multicellular life. Plants had already invaded Diadem"s land, and some animals-the equivalents of arthropods, molluscs and worms-had begun to follow in their wake. The largest land-based animals were still small by terrestrial standards, since nothing in the oceans had yet evolved an internal skeleton. There was nothing that showed any signs of intelligence, but that was only a minor disappointment. It would still take a lifetime"s study just to explore the fantastic array of body-plans, metabolisms and survival strategies which Diadem life had blindly evolved.

Yet even before Galiana had sent down the first survey shuttles, a shattering truth had become apparent.

Someone had reached Diadem before them.

The signs were unmistakable; glints of refined metal on the surface, picked out by radar. Upon inspection from orbit they turned out to be ruined structures and equipment, obviously of human origin.

"It"s not possible," Clavain had said. "We"re the first. We have to be the first. No one else has ever built anything like the Sandra Voi; nothing capable of traveling this far."

"Somewhere in mere," Galiana had answered, "I think there might be a mistaken a.s.sumption, don"t you?"

Meekly, Clavain had nodded.

Now-later still man he had promised-Clavain made his way back to the waiting shuttle. The red carpet of safety led straight to the access ramp beneath the craft"s belly. He climbed up and stepped through the transparent membrane which spanned the entrance door, most of his suit slithering away on contact with the membrane. By the time he was inside the ship he wore only a lightweight breather mask and a few communicational devices. He could have survived outside naked for many minutes-Diadem"s atmosphere now had enough oxygen to support humans-but Galiana refused to allow any intermingling of microorganisms.

He returned the equipment to a storage locker, placed the worm sample in a refrigeration rack, and clothed himself in a paper-thin black tunic and trousers, before moving into the aft compartment where Galiana was waiting.

She and Felka were sitting facing each other across the blank-walled, austerely furnished room. They were staring into the s.p.a.ce between them without quite meeting each other"s eyes. They looked like a mother and daughter locked in argumentative stalemate, but Clavain knew better.

He issued the mental command, well rehea.r.s.ed now, which opened his mind to communion with the others. It was like opening a tiny aperture in the side of a dam; he was never adequately prepared for the force with which the flow of data hit him. The room changed; color bleeding out of the walls, lacing itself into abstract structures which permeated the room"s volume. Galiana and Felka, dressed dourly a moment earlier, were now veiled in light, and appeared super-humanly beautiful. He could feel their thoughts, as if he were overhearing a heated conversation in the room next door. Most of it was nonverbal; Galiana and Felka playing an intense, abstract game. The thing floating between them was a solid lattice of light, resembling the plumbing diagram of an insanely complex refinery. It was constantly adjusting itself, with colored flows racing this way and that as the geometry changed. About half the volume was green; what remained was lilac, but now the former encroached dramatically on the latter.

Felka laughed; she was winning.

Galiana conceded and crashed back into her seat with a sigh of exhaustion, but she was smiling as well.

"Sorry. I appear to have distracted you," Clavain said.

"No; you just hastened the inevitable. I"m afraid Felka was always going to win."

The girl smiled again, still saying nothing, though Clavain sensed her victory; a hard-edged thing which for a moment outshone all other thoughts from her direction, eclipsing even Galiana"s air of weary resignation.

Felka had been a failed Conjoiner experiment in the manipulation of fetal brain development; a child with a mind more machine than human. When he had first met her-in Galiana"s nest on Mars-he had encountered a girl absorbed in a profound, endless game; directing the faltering self-repair processes of the terraforming structure known as the Great Wall of Mars, in which the nest sheltered. She had no interest in people-indeed; she could not even discriminate faces. But when the nest was being evacuated, Clavain had risked his life to save hers, even though Galiana had told him that the kindest thing would be to let her die. As Clavain had struggled to adjust to life as part of Galiana"s commune, he had set himself the task of helping Felka to develop her latent humanity. She had begun to show signs of recognition in his presence, perhaps sensing on some level that they had a kinship; that they were both strangers stumbling toward a strange new light.

Galiana rose from her chair, carpets of light wrapping around her. "It was time to end the game, anyway. We"ve got work to do." She looked down at the girl, who was still staring at the lattice. "Sorry, Felka. Later, maybe."

Clavain said: "How"s she doing?"

"She"s laughing, Nevil. That has to be progress, doesn"t it?"

"I"d say that depends what she"s laughing about."

"She beat me. She thought it was funny. I"d say that was a fairly human reaction, wouldn"t you?"

"I"d still be happier if I could convince myself she recognized my face, and not my smell, or the sound my footfalls make." "You"re the only one of us with a beard, Nevil. It doesn"t take vast amounts of neural processing to spot that."

Clavain scratched his chin self-consciously as they stepped through into the shuttle"s flight deck. He liked his beard, even though it was trimmed to little more than gray stubble so that he could slip a breather mask on without difficulty. It was as much a link to his past as his memories, or the wrinkles Galiana had studiously built into his remodeled body.

"You"re right, of course. Sometimes I just have to remind myself how far we"ve come."

Galiana smiled-she was getting better at that, though there was still something a little forced about it-and pushed her long, gray-veined black hair behind her ears. "I tell myself the same things when I think about you, Nevil."

"Mm. But I have come some way, haven"t I?"

"Yes, but that doesn"t mean you haven"t got a considerable distance ahead of you. I could have put that thought into your head in a microsecond, if you allowed me to do so-but you still insist that we communicate by making noises in our throats, the way monkeys do."

"Well, it"s good practice for you," Clavain said, hoping that his irritation was not too obvious.

They settled into adjacent seats while avionics displays slithered into take-off configuration. Clavain"s implants allowed him to fly the machine without any manual inputs at all, but-old soldier that he was-he generally preferred tactile controls. So his implants obliged; hallucinating a joystick inset with b.u.t.tons and levers, and when he reached out to grasp it his hands seemed to close around something solid. He shuddered to think how thoroughly his perceptions of the real world were being doctored to support this illusion; but once he had been flying for a few minutes he generally forgot about it, lost in the joy of piloting.

He got them airborne, then settled the shuttle into level flight toward the fifth ruin that they would be visiting today. Kilometers of ice slid beneath them, only occasionally broken by a protruding ridge or a patch of dry, boulder-strewn ground.

"Just a few shacks, you said?"

Galiana nodded. "A waste of time, but we had to check it out."

"Any closer to understanding what happened to them?"

"They died, more or less overnight. Mostly through incidents related to the breakdown of normal thought-although one or two may have simply died; as if they had some greater susceptibility to a toxin than the others."

Clavain smiled, feeling that a small victory was his. "Now you"re looking at a toxin, rather than a psychosis?"

"A toxin"s difficult to explain, Nevil."

"From Martin Setterholm"s worms, perhaps?"

"Not very likely. Their biohazard containment measures weren"t as good as ours-but they were still adequate. We"ve a.n.a.lyzed those worms and we know they don"t carry anything obviously hostile to us.

And even if there was a neurotoxin, how would it affect everyone so quickly? Even if the lab workers had caught something, they"d have fallen ill before anyone else did, sending a warning to the others-but nothing like that happened." She paused, antic.i.p.ating Clavain"s next question. "And no; I don"t think that what happened to them is necessarily anything we need worry about, though that doesn"t mean I"m going to rule anything out. But even our oldest technology"s a century ahead of anything they had-and we have the Sandra Voi to retreat to if we run into anything the medichines in our heads can"t handle."

Clavain always did his best not to think too much about the swarms of sub-cellular machines lacing his brain-supplanting much of it, in fact-but there were times when it was unavoidable. He still had a squeamish reaction to the idea, though it was becoming milder. Now, though, he could not help but view the machines as his allies; as intimately a part of him as his immune system. Galiana was right: they would resist anything which tried to interfere with what now pa.s.sed as the "normal" functioning of his mind.

"Still," he said, not yet willing to drop his pet theory. "You"ve got to admit something: the Americans-Setterholm especially-were interested in the worms. Too interested, if you ask me."

"Look who"s talking." "Ah, but my interest is strictly forensic. And I can"t help but put the two things together. They were interested in the worms. And they went mad."

What he said was an oversimplification, of course: it was clear enough that the worms had only preoccupied some of the Americans: those who were most interested in xen.o.biology. According to the evidence the Conjoiners had so far gathered, the effort had been largely spearheaded by Setterholm, the man he had found dead at the bottom of the creva.s.se. Setterholm had traveled widely across Diadem"s snowy wastes, gathering a handful of allies to a.s.sist in his work. He had found worms in dozens of ice-fields, grouped into vast colonies. For the most part the other members of the expedition had let him get on with his activities, even as they struggled with the day-to-day business of staying alive in what was still a hostile, alien environment.

Even before they had all died things had been far from easy. The self-replicating robots which had brought them here in the first place had failed years before, leaving the delicate life-support systems of their shelters to slowly collapse; each malfunction a little harder to rectify than the last. Diadem was getting colder, too-sliding inexorably into a deep ice-age. It had been the Americans" misfortune to arrive at the coming of a great, centuries-long winter. Now, Clavain thought, it was colder still; the polar ice-caps rushing toward each other like long-separated lovers.

"It must have been fast, whatever it was," Clavain mused. "They"d already abandoned most of the outlying bases by then, huddling together back at the main settlement. By then they only had enough spare parts and technical know-how to run a single fusion power-plant."

"Which failed."

"Yes-but that doesn"t mean much. It couldn"t run itself, not by then-it needed constant tinkering.

Eventually the people with the right know-how must have succ.u.mbed to the ... whatever it was-and then the reactor stopped working and they all died of the cold. But they were in trouble long before the reactor failed."

Galiana seemed on the point of saying something. Clavain could always tell when she was about to speak; it was if some leakage from her thoughts reached his brain even as she composed what she would say.

"Well?" he said, when the silence had stretched long enough.

"I was just thinking," she said. "A reactor of that type-it doesn"t need any exotic isotopes, does it?

No tritium, or deuterium?"

"No. Just plain old hydrogen. You could get all you needed from sea-water."

"Or ice," Galiana said.

They vectored in for the next landing site. Toadstools, Clavain thought: half a dozen black metal towers of varying height surmounted by domed black habitat modules, interlinked by a web of elevated, pressurized walkways. Each of the domes was thirty or forty meters wide, perched a hundred or more meters above the ice, festooned with narrow, armored windows, sensors and communications antennae.

A tonguelike extension from one of the tallest domes was clearly a landing pad. In fact, as he came closer, he saw that there was an aircraft parked on it; one of the blunt-winged machines that the Americans had used to get around in. It was dusted with ice, but it would probably still fly with a little persuasion.

He inched the shuttle down, one of its skids only just inside the edge of the pad. Clearly the landing pad had only really been intended for one aircraft at a time.

"Nevil..." Galiana said. "I"m not sure I like this."

He felt tension, but could not be sure if it was his own or Galiana"s, leaking into his head.

"What don"t you like?"

"There shouldn"t be an aircraft here," Galiana said.

"Why not?"

She spoke softly, reminding him that the evacuation of the outlying settlements had been orderly, compared to the subsequent crisis. "This base should have been shut down and mothballed with all the others." "Then someone stayed behind here," Clavain suggested.

Galiana nodded. "Or someone came back."

There was a third presence with them now; another hue of thought bleeding into his mind. Felka had come into the c.o.c.kpit. He could taste her apprehension.

"You sense it, too," he said, wonderingly, looking into the face of the terribly damaged girl. "Our discomfort. And you don"t like it anymore than we do, do you?"

Galiana took the girl"s hand. "It"s all right, Felka."

She must have said that just for Clavain"s benefit. Before her mouth had even opened Galiana would have planted rea.s.suring thoughts in Felka"s mind; attempting to still the disquiet with the subtlest of neural adjustments. Clavain thought of an expert Ikebana artist minutely altering the placement of a single flower in the interests of harmony.

"Everything will be OK," Clavain said. "There"s nothing here that can harm you."

Galiana took a moment, blank-eyed, to commune with the other Conjoiners in and around Diadem.

Most of them were still in orbit observing things from the ship. She told them about the aircraft and notified them that she and Clavain were going to enter the structure.

He saw Felka"s hand tighten around Galiana"s wrist.

"She wants to come as well," Galiana said.