To go forward or to go back?

Tris was still debating this question when the light ambled towards her and the answer became irrelevant. Compared to transparent jets, high-sided gorges and hunger so sharp it hurt, a knee-high stag with luminous antlers counted for less than zero.

Tiny fluorescent bonsai topped its lowered head and one front hoof pawed angrily at the damp grass in open threat, but Tris found it hard to take seriously a stag no higher than her hips, antlers included. Besides, she already knew about the petit juc; they appeared regularly enough in those sickly little feeds about the Emperor.

"Shoo," said Tris.

When the stag refused to move Tris decided to walk round it, which was how she found herself at the brow of a hill, staring towards a second, far brighter light.

"Now what?"

Rapture was known to be empty except for the three overlapping, interlinked areas of the city itself. No one lived in the walled palace except Chuang Tzu, his eunuchs, guards and servitors. A child of five knew that. The two outer cities looked from the air exactly like a single cell dividing down the middle, assuming both halves of a cell could be square and one half could contain the families of the servitors, the soldiers' camp followers and the shopkeepers, tradespeople and artisans needed to feed and clothe the inhabitants of the other, which housed the 2022 ambassadors to the Celestial Throne.

Maybe guards had been sent out to see if anyone had survived the crash, except it wasn't really a crash, more a bad landing, and those jets had obliterated the physical carcass of All Tomorrow's Parties along with the very water in which it sunk.

Tris hated not knowing what was going on. In fact, Tris hated it so much that most of the time she refused to admit to herself this was even a possibility. There were good reasons for that, reasons she studiously avoided, because if you didn't avoid them then the reasons had won.

"Fuck it," said Tris. Here she was, almost hallucinating with hunger, having been threatened by some midget stag with lights for antlers and still days away from where she needed to be, and already she was too scared to investigate what would probably turn out to be marsh gas or something equally stupid.

One of the first laws of exploring new worlds proved to be that it is a lot easier to walk uphill in the dark than it is to go down. Tris discovered this at the point her heel skidded on wet moss and she lost her balance, landing with a splash at the bottom of an absurdly short slope.

The light looked no closer but the grass was firm underfoot and the ground rose gently, so Tris set one shaky foot in front of the other and tuned her brain to a place where she'd crashed All Tomorrow's Parties slap bang in the middle of the imperial pavilions and mowed down the charging bannermen with a laser pistol she discovered at the very last minute, right next to the exit hatch.

Tris had once held a laser pistol.

It was very small and incredibly old. A collector's item, the owner said. He'd arrived one morning carrying a talking doll for her, a necklace of ever-changing stones for her mother and a knife for her father, even though everyone knew he was long gone and never coming back. Tris had hidden the knife when the grown-ups were talking and neither the man nor her mother ever asked where it went.

In the months to come Tris got a silver book and a bracelet which could answer questions on any subject beginning with a letter between "F" and "L." And for a while her mother was happy and their shack contained more food than Tris could ever remember seeing.

Sweet, sour and sometimes both, there were tastes and consistencies that worked perfectly while seeming to contradict each other. Cayenne ice cream, battered snails.

Endless food. New clothes.

It ended one morning when Tris trotted through to the kitchen to get some grapes and found instead the man standing at their small table, wrapping bread in the kind of foil that heated itself on demand. You just said the words and left it for thirty seconds. All explorers used it, he said. At least all explorers like him.

"You're going home..." Tris said.

Opalescent eyes looked at her, almost puzzled.

"How old are you?"

"Five."

"And how do you know I'm going?"

"Because I do," said Tris. She was still called Tristesse then. A name he'd casually attached to the sad-eyed brat after the first few days of living with her mother.

"Why don't you take me with you?" Tristesse suggested.

The man smiled. "You know what? I'm going to miss you." Putting his hands under Tris's arms, he lifted the child with one easy motion and stood her on the table next to the bread, so she could stare into eyes which were almost white and flecked with a thousand colours. "I really am."

"Why did you come here anyway?" It seemed an obvious question. Although from the look on the man's face you'd have thought it was the last thing he expected to be asked.

"I'm an artist," he said.

"Not an explorer?"

"Both," he said with a smile.

Tris thought about that. "What's an artist?"

"Someone who..." The man hesitated, as if debating the question with himself. "I collect objects," he said, "then wrap them up in memories and knot each one into a web."

"Did you find what you wanted?"

"Oh yes," he said, "you're one knot on the spider's web. A very special knot." Lifting her down, he picked up his bag. It was really a tube, almost as tall as she was, sealed at the bottom and sticky around the top. Tris had never seen another like it.

"You can keep the knife you stole," he said. "I've got this." And he produced the pistol, an intricate fusion of crystal and metal, so delicate that it could have been made by a spider itself.

Tris looked embarrassed.

"See you," he said.

"Will you?" Tris asked.

The man shook his head. "Probably not."

One step became another as Tris had walked her way through half a dozen daydreams and a fistful of memories, most of them making about as much sense in replay as they did the first time round.

The light, meanwhile, remained in the distance and with morning it vanished altogether. Tris wasn't too sure she could maintain her direction without the light to guide her. Equally, staying put meant losing a whole day's walking. So in the end Tris compromised. She walked all morning across grassland that climbed towards distant hills and then, come midday, she stopped, mostly because that way if she'd got the direction wrong she wouldn't have too far to walk back.

As compromises went it was barely adequate.

Making camp took Tris less time than it might have done if she'd been sensible enough to rescue anything useful from the yacht. "Get over it," Tris told herself. She'd had this discussion already and been forced to admit that rescuing more than herself would have been impossible. So she walked slowly around a huge boulder that protruded from the grass like weathered bone until she was sure which way the wind blew and then settled herself on the opposite side.

The third nightfall was less impressive than the second, which mirrored a rule Tris had already identified; new emotions devalued, going from intense through familiar to reach a kind of ghost state where one no longer really noticed them at all.

With darkness came the light and Tris was grateful, because it meant she'd been walking in the right direction after all. And the light might appear to be in the same place but Tris wasn't, because she was closer and that made her happy too.

Straightening her top and hitching up her frayed trousers, Tris set off uphill and walked until her foot hurt and then walked some more. The grass beneath her toes, having become soft, became rough again and began to alternate with heather and thorn. Tris had seen neither in real life. Heliconid lacked soil or open places where unnecessary plants could grow and had no ambassador to the Celestial Throne who could request help from the Library. All of the food in Heliconid came from the boxes or was raised on the levels under strip light.