"He wouldn't have been worth the effort," I said, reaching over to pick up the thing which had slipped from his pocket. No weapon, I saw now-or at least nothing with which I was familiar.

It was more like a syringe, containing some fluid which could have been black or dark-red, but was most likely the latter.

"What's this?"

"Something he shouldn't have had in Idlewild. Give it to me, will you? I'll have it destroyed."

I passed the hypodermic device willingly; it was of no use to me. As she pocketed it with something close to revulsion, Amelia said, "Tanner, he'll be back, when you've left us."

"We'll worry about that later-and I'm not going anywhere in a hurry, am I? Not with my memory in the state it is." Trying to lighten the mood, I added, "You said something about showing me my face, earlier on."

She answered hesitantly. "Yes, I did, didn't I?" Then she fished out the little penlight she had used in the tunnel and instructed me to kneel down again, looking into the glass. When Yellowstone and its moon had gone by and the cave had become dark again, she shone the torch on my face. I looked at my reflection in the glass.

There was no shocking sense of unfamiliarity. How could there have been, when I had already traced the outline of my face with my fingers a dozen times since waking? I already sensed that my face would be blandly handsome, and that was the case. It was the face of a moderately successful actor or a motivationally suspect politician. A dark-haired man in his early forties-and, without quite knowing from where I had dredged this fact, I knew that on Sky's Edge, that more or less meant exactly what it said; that I could not be drastically older than I seemed, for our methods of longevity extension lagged centuries behind the rest of humanity.

Another shard of memory clicking into place.

"Thank you," I said, when I had seen enough for now. "I think that helped. I don't think my amnesia's going to last forever."

"It almost never does."

"Actually, I was being flippant. Are you saying there are people who never get their memories back?"

"Yes," she said, with unconcealed sadness. "Mostly, they never function well enough to immigrate."

"What happens to them, in that case?"

"They stay here. They learn to help us; to cultivate the terraces. Sometimes they even jointhe Order."

"Poor souls."

Amelia stood, beckoning me to follow her. "Oh, there are worse fates, Tanner. I should know."

SIX.

Ten years old, he moved with his father across the curved, polished floor of the freight bay, their booted feet squeaking on the high-gloss surface, the two of them suspended above their own dark reflections; a man and a boy forever walking up what looked to the eye like an ever-steepening hill, but which always felt perfectly level.

"We're going outside, aren't we?" Sky said.

Titus looked down at his son. "Why do you assume that?"

"You wouldn't have brought me here otherwise."

Titus said nothing, but the point could not be denied. Sky had never been in the freight bay before; not even during one of Constanza's illicit trips into the Santiago's forbidden territory.

Sky remembered the time she had taken him to see the dolphins, and the punishment that had ensued, and how that punishment had been eclipsed by the ordeal that had followed: the flash of light and the period he had spent trapped alone and cold in the utter darkness of the nursery. It seemed so long ago, but there were still things about that day that he did not fully understand now; things he had never persuaded his father to speak about. It was more than his father's recalcitrance; more than simply Titus's grief at the death of Sky's mother.

The censorship by omission-it was more subtle than a simple refusal to discuss the incident-extended to every adult Sky had spoken to. No one would speak of that day when the whole ship had turned dark and cold, yet to Sky the events were still clearly fixed in his memory.

After what felt like days-and now that he thought about it, it probably had been days-the adults had made the main lights come on again. He noticed when the air-circulators began to work-a faint background ambience which he had never really noticed until it had ceased.

In all that time, his father told him later, they had been breathing unrecirculated air; slowly turning staler and staler as the hundred and fifty waking humans dumped more and more carbon dioxide back into their atmosphere. In a few more days it would have started causing serious problems, but now the air became fresher and the ship slowly warmed back up to the point where it was possible to move along the corridors without shivering.

Various secondary systems that had been unavailable during the blackout were brought hesitantly back online. The trains which ferried equipment and technicians up and down the spine began to run again. The ship's information nets, which had been silent, could now be queried. The food improved, but Sky had hardly noticed that they had been eating emergency rations during the blackout.

Yet still none of the adults would discuss exactly what had happened.

Eventually, when something like normal shipboard life had returned, Sky managed to sneak back into the nursery. The room was lit, but to his surprise everything looked more or less as he had left it: Clown frozen in that strange shape he had assumed after the flash. Sky had crept closer to examine the distorted form of his friend. He could see now that all Clownhad ever been was a pattern in the tiny coloured squares that covered the nursery's walls, floor and ceiling. Clown had been a kind of moving picture that only made sense-only looked right -when seen from precisely Sky's point of view. Clown had appeared to be physically present in the room-not simply drawn on the wall-because his feet and legs had been drawn on the floor as well, but with a perspective distorted such that it looked perfectly real from where Sky happened to be. The room must have mapped Sky and his direction of gaze. Had he been able to shift his viewpoint fast enough, faster than the room could recompute Clown's image, he would perhaps have seen through that trick of perspective.

But Clown was always much faster than Sky. For three years, he had never doubted that Clown was real, even if Clown could never touch or be touched by anything.

His parents had abdicated responsibility to an illusion.

Now, however-in a mood of eager forgiveness-he pushed such thoughts from his mind, awed by the sheer size of the freight bay and the prospect of what lay ahead. What made the place all the larger was the fact that the two of them were quite alone, surrounded only by a puddle of moving light. The rest of the chamber was suggested rather than clearly seen; its dimensions hinted at by the dark, looming shapes of cargo containers and their associated handling machines along curved lines into blackness. Parked here and there were various spacecraft; some little more than single-person tugs or broomsticks designed for flying immediately outside the ship, while others were fully pressurised taxi craft, built for crossing to the other Flotilla craft. The taxis could enter an atmosphere in an emergency, but they were not designed to make the return trip to space. The delta-winged landers which would make multiple journeys down to the surface of Journey's End were too large to store inside the Santiago; they were attached instead to the outside of the ship and there was almost no way to see them unless you worked on one of the external work crews, as his mother had done before her death.

Titus halted near one of the small shuttles. "Yes," he said, "we're going outside. I think it's time you saw things the way they really are."

"What things?"

But by way of answer Titus only elevated the cuff of his uniform and spoke quietly into his bracelet. "Enable excursion vehicle 15."

There was no hesitation; no querying of his authority. The taxi answered him instantly, lights flicking on across its wedge-shaped hull, its cockpit door craning open on smooth pistons and the pallet on which it was mounted rotating to bring the door closer and align the vehicle with its departure track. Steam started to vent from ports spaced along the vehicle's side and Sky could hear the growing whine of turbines somewhere inside the machine's angular hull. A few seconds ago the thing had been a piece of sleek, dead metal, but now there were awesome energies at its disposal; barely contained.

He hesitated at the door, until his father beckoned that he lead.

"After you, Sky. Go forward and take the seat on the left of the instrument column. Don't touch anything while you're about it."

Sky hopped into the spacecraft, feeling the floor vibrating beneath his feet. The taxi was considerably more cramped inside than it had looked-the hull was thickly plated and armoured-and he had to duck and dive to reach the forward seats, brushing his head against a gristle-like tangle of internal pipework. He found his seat and fiddled with the blue-steel buckle until he had it tight across his chest. In front of him was a cool turquoise-green display-constantly changing numbers and intricate diagrams-beneath acurved, gold-tinted window. To his left was a control column inset with neat levers and switches and a single black joystick.

His father settled into the rightmost seat. The door had closed on them now and suddenly it was quieter, save for the continuous rasp of the taxi's air-circulation. His father touched the green display with his finger, making it change, studying the results with narrow-eyed concentration.

"Word of advice, Sky. Never trust these damned things to tell you that they're safe. Make sure for yourself."

"You don't trust machines to tell you for yourself?"

"I used to, once." His father eased the joystick forward and the taxi commenced gliding along its departure track, sliding past the parked ranks of other vehicles. "But machines aren't infallible. We used to kid ourselves that they were because it was the only way to stay sane in a place like this, where we depend on them for our every breath. Unfortunately, it was never true."

"What happened to change your mind?"

"You'll see, shortly."

Sky spoke into his own bracelet-it offered a limited subset of the capabilities of his father's unit-and asked the ship to connect him to Constanza. "You'll never guess where I'm calling from," he said when her face had appeared, tiny and bright. "I'm going outside."

"With Titus?"

"Yes, my father's here."

Constanza was thirteen now, although-like Sky-she was often taken to be older. In neither case had the assumption much to do with their looks, for while Constanza at least looked no older than her true age, Sky looked substantially younger than his: small and pale and difficult to imagine being afflicted by adolescence in anything like the near future. But both were still intellectually precocious; Constanza was now working more or less fulltime within Titus's security organisation. As was naturally the case aboard a ship with such a small living crew, her duties generally had little to do with enforcement of rules and much more to do with the overseeing of intricate safety procedures and the studying and simulating of operational scenarios. And while it was demanding work-the Santiago was a phenomenally complex thing to understand as a single entity-it was almost certainly work that had never required Constanza to leave the confines of the ship. Since she had begun working for his father, their friendship had become more tenuous-she had responsibilities Sky lacked, and moved in the adult world-but now he was about to do something that could not help but impress her; something that would elevate him in her eyes.

He waited for her answer, but when it came it was not quite what he had been expecting, "I'm sorry for you, Sky. I know it won't be easy, but you have to see it, I think."

"What are you talking about?"

"What Titus is about to show you." She paused. "I've always known, Sky. Ever since it happened, the day we got back from the dolphins. But it was never something it was right to talk about. When you come back inside, you can talk to me about it, if you want."

He seethed; the way she spoke was less like a friend than what he imagined acondescending older sister might be like. And now his father compounded it by placing a comforting hand on his forearm. "She's right, Sky. I wondered if I should forewarn you, then in the end decided not to-but what Constanza has said is true. It won't be pleasant, but the truth seldom is. And I think you're ready for it now."

"Ready for what?" he said, and then realised the link to Constanza was still open. He addressed her: "You knew this trip was going ahead, didn't you?"

"She had some idea that I'd be taking you outside," his father said, before the girl could defend herself. "That's all. You mustn't-can't-blame her for that. It's a flight outside the ship; everyone in security has to know about it, and-since we're not crossing over to one of the other ships-the reason for it."

"Which is?"

"To learn what happened to your mother."

All the while they had been moving, but now they reached the freight bay's sheer metal wall.

A circular door in the wall whisked open to admit them, the taxi sliding off its pallet into a long, red-lit chamber not much wider than the machine itself. They waited there for a minute or so while the chamber's air was sucked out, then the taxi moved downwards abruptly, sinking into a shaft. Sky's father took the opportunity to lean over to adjust Sky's belt, and then they were outside the ship-blackness below, and the gentle curve of the hull above their heads. The feeling of vertigo was quite intense, even though there was nothing below to suggest height.

They dropped. It was only for an instant, but it was nauseating enough; like the feeling Sky remembered from the rare times when he had been near the ship's centre, where gravity dwindled almost to zero. Then the taxi's engines kicked in, and something like weight returned. Expertly his father vectored the taxi away from the looming grey bulk of the massive ship, adjusting their course with taps of steering thrust, his fingers as delicate on the controls as a concert pianist's.

"I feel sick," Sky said.

"Close your eyes. You'll be fine in a moment."

Despite the disquiet he felt about his mother's death-and the fact that this trip had something to do with it-Sky could not completely suppress a thrill of excitement at the thought of being outside. He released the safety buckle and started clambering all around the taxi to get a better view.

His father scolded him gently and told him to get back in his seat, but not with any great conviction. Then he yawed the taxi around and smiled as the great ship they had just left came into sight.

"Well, there she is. Your home for the last ten years, Sky, and the only home I've ever known.

I know; there's no need to hide your feelings. She's not exactly beautiful, is she?"

"She's big, though."

"She'd better be-she's just about all we'll ever have. You're luckier than me, of course. At least you'll see Journey's End."

Sky nodded, but his father's quiet certainty that he would be dead by then could not help but make him feel sad. He looked back to the ship.

The Santiago was two kilometres long; longer than any ship which had ever sailed any of Earth's oceans and easily the equal of any of the largest craft which had plied the solar system in the days before the Flotilla's departure. Her skeleton, in fact, was an old fusion-drive space freighter, retrofitted for a journey into interstellar space. With small variations, the other Flotilla ships had been converted from the same sources.

This far from any star, almost no light fell upon the ship, and she would have been invisible were it not for the light spilling from tiny windows dotted along her length. At the very front was a big sphere encircled by lights. That was the command section, where the bridge was, and where the crew spent most of their time when they were on duty. It was where the navigational and scientific instruments were kept, forever pointed towards the destination star; the one they had nicknamed Swan, but which Sky knew really had the much less poetic name 61 Cygni-A: one cool red half of a binary star system located in the random sprinkle of stars which had been given the name Cygnus in antiquity. Only towards the end of the voyage would the ship flip around to bring its tail to bear on Swan, so that it could slow itself down with exhaust thrust from the engines.

Behind the control sphere was a cylinder of the same diameter, which held the freight bay from which they had just come. Beyond that was a long, thin spine, studded with regularly spaced modules like immense dinosaur vertebrae. At the very end of the spine was the propulsion system, the intricate and fearsome engines which had once burned to accelerate the ship up to its present cruising speed, and which would burn again on some immeasurably remote day when Sky was fully grown.

Sky knew all these aspects of the ship; he had seen models and holograms of it many times, but it was something else to be seeing it for himself, from outside, for the first time.

Slowly, but with grinding stateliness, the whole ship was rotating on its long axis, spinning to create the illusion of gravity on its curving decks. Sky watched it turn; watched lights hove into view and disappear ten seconds later. He could see the tiny aperture in the cargo cylinder, where the taxi had departed. It looked very small, but not perhaps as small as it should have done, given that this ship was all his world could ever be. Almost. He was young now, and he had only been allowed to explore a small fraction of the Santiago, but surely it would not be long before he knew it all intimately.

He noticed something else, too; something that the models and the holos had definitely not got right. As the ship turned, it looked darker on one side than the other.

What could that mean?

But almost as soon as the troubling inconsistency had begun to worry him, he had forgotten it; marvelling in the sheer immensity of the ship; the pin-sharp way the details held their clarity across kilometres of vacuum; trying to imagine where his favourite places in the ship mapped into this strange new view. He had never been very far down the spine, that was for certain, and even then only under Constanza's guidance, some daredevil adventure before the adults caught them. No one had really blamed him for that, however. It was natural curiosity to want to see the dead, once their existence was known.

Of course, they were not really dead-just frozen.

The spine was a kilometre long; half the ship's total length. In cross-section it had a hexagonal form, with six long, narrow sides. Along each of those sides were spaced sixteen sleeper modules; each a disk-shaped structure rooted to the spine by umbilical attachments. Ninety-six disks in total, and each of those disks, Sky knew, contained tentriangular compartments, each of which held a single momio sleeper and the bulky machines necessary for their care. Nine hundred and sixty frozen passengers, then. Nearly a thousand people in total, all submerged in an icy sleep which would last the entire duration of the voyage to Swan. The sleepers, needless to say, were the most precious commodity that the ship carried; its sole reason for existence. The one hundred and fifty-strong living crew were there only to ensure the wellbeing of the frozen and to keep the ship on course. Again Sky measured his current familiarity with the ship against that which he could reasonably hope to attain by the time he was an adult. At the moment he knew fewer than a dozen people, but that was only because his upbringing had been deliberately sheltered. Soon he would know many of the others. His father said that there were one hundred and fifty warm humans on the ship because that was some kind of magic number in sociological terms; the population size towards which village communities tended to converge and which carried with it the best prospects for internal harmony and general wellbeing amongst its members. It was large enough to allow individuals to move in slightly different circles if they wished, but not so large that there were likely to be dangerous internal schisms. In that sense, Old Man Balcazar was the tribal leader and Titus Haussmann, with his deep knowledge of secret lore and his abiding concern for the safety of the population, chief medicine man, or top hunter, perhaps. Either way, Sky was the son of someone in a position of authority, what the adults sometimes called a caudillo, meaning big man, and that augured well for his own future. It was open talk amongst his parents and the other adults that Captain Balcazar was an "old man" now. Old Man Balcazar and his father were professionally close: Titus always had the Captain's ear and Balcazar routinely consulted Sky's father for advice. This trip outside would have required Balcazar's authorisation, since use of any of the Santiago's spacecraft was to be kept to a minimum, the ships themselves irreplaceable.

He felt the taxi decelerate, false gravity easing off again.

"Take a good look," Titus said.

They were passing the engines: a huge and bewildering tangle of tanks and pipes and flared orifices, like the gaping mouths of trumpets.

"Antimatter," Titus said, mouthing the word like a quiet oath. "It's the devil's own stuff, you know. We carry a small amount even in this shuttle, just to initiate fusion reactions, but even that makes me shiver. But when I think about the amount aboard the Santiago, the hairs on the back of my neck stand up."

Titus pointed to the two magnetic storage bottles at the rear of the ship: huge reservoirs for penning macroscopic quantities of pure antilithium. The larger of the two reservoirs was empty now, the fuel it had contained completely consumed during the initial boost phase up to interstellar cruising speed. Though there was no external indication that this was the case, the second bottle still contained its complete load of antimatter, delicately balanced in a vacuum fractionally more perfect than the one through which the great ship flew. There was less antimatter in the smaller bottle, since the ship's mass would be less during deceleration than acceleration, but there was still enough to give anyone nightmares.

No one, at least in Sky's experience, ever joked about antimatter.

"All right," his father said. "Now get back in your seat and do your belt up."

When he was secure Titus gunned the taxi, increasing the thrust to its maximum. The Santiago diminished until it was just a thin grey sliver, and then became difficult to see unless one searched the starfields carefully. It was hard to believe, seeing it againstapparently fixed stars, that the ship was moving at all. It was, but eight hundredths of lightspeed, though faster than any crewed ship had ever moved before, was still almost zero when set against the vast distances between the stars.

That was why the passengers were frozen, so that they could sleep out the whole thing while three generations of crew lived almost their entire lives tending them. Cocooned in their cryogenic sleeper berths, the passengers were nicknamed mummies by the crew, momios in the Castellano which was still used for casual conversation within the ship.

Sky Haussmann was crew. So was everyone he knew.

"Can you see the other ships yet?" asked his father.

Sky searched the forward view for long moments before finding one of the other vessels. It was hard to see, but his eyes must have adapted to the darkness since leaving home. Had he imagined it, even so?

No-there it was again, a tiny, toylike constellation in its own right.

"I see one." Sky pointed.

His father nodded. "That's the Brazilia, I think. The Palestine and the Baghdad are out there too, but they're much further away."

"Can you see it?"

"Not without a little assistance." Titus's hands moved in the dark across the taxi's control board, painting an overlay of coloured lines over the window, bright against space like chalk on a blackboard. The lines boxed the Brazilia and the two more distant ships, but it was only when the Brazilia loomed large that he thought he could make out the slivers of the other two vessels. By then the Brazilia had revealed itself to be identical to his home ship, down to the disks studding its spine.