And the General had enough guards. Chuang Tzu had seen them exercising in front of the Wu-Men, a gate so vast that an entire army could muster in its shadow. Although why an assassin should want to kill the ruler of the richest, most cultured empire history had ever known was a mystery that Chuang Tzu hoped soon to have unravelled, once the two of them met.

In the meantime he had his dreams.

Dreams of a far stranger assassin arrested on the point of failure and put to questioning. It happened in a place of walls like the walls which surrounded Chuang Tzu's city, only these were of beaten earth, lime dust and straw and the sun overhead was hotter than the one Chuang Tzu knew.

The streets of this city were dirty and the trees lining the wider roads were shrivelled from drought and burnt along the edges of their fronds, but the walls of both cities had one distinct similarity, despite their difference in magnificence and construction.

Both were red.

Because the Chuang Tzu knew that meaning could be found within coincidence and his daydreams were as significant as any which came in the night, he considered this point seriously and decided that the redness of the walls was probably important. And there was a chance, not a good chance admittedly, that he might come to understand this significance before he was killed.

It would be a short reign, merely twenty years, and an inglorious one. And its end would be as strange as its start, which began with a butterfly and a small boy being sent to bed without supper.

Mirrored eyes had swallowed the sight of endless, utterly identical small boys, a million Zaqs. The butterfly who stared at him was red, the size of a small plate and had fat black spots on each wing, though when Zaq looked closely he realized the spots were somewhere between purple and ultraviolet, their edges both fractal and recursive.

There was a difference, apparently.

Zaq had never met a butterfly the size of a bird. Actually, he wasn't sure he'd ever met a bird.

"In the Carboniferous period," said the butterfly, "even mayflies had wingspans this big. Mind you, back then there was so much oxygen in the atmosphere that forests burned when wet..."

That was when Zaq knew he was dreaming.

"Yes and no," the butterfly said.

It rested on the edge of Zaq's bed, which was actually a door that was held off the ground by rocks at each corner. A hundred or so holes had been drilled in the door, a hand-breadth apart, so that Zaq's mattress could breath. His brother Eli was very proud of this.

The butterfly looked around.

And what it saw, kaleidoscope-like through the endless facets of its silver eyes, was what it expected to see. A shitty little shack built from sheet plastic and cheap blocks of polycrete, roofed with a rancid canvas awning in what had once been a landing pad for hoppers.

There were two ways the butterfly knew this. The first was that a faded "H" could still be seen etched into the ledge on which Zaq's mother had built her house, the second was that the butterfly could remember when Rip had briefly been fashionable. In those days tiny silver hoppers had buzzed around the non-world like blowflies.

Opinion was divided on Rip's exact provenance, but then opinion in the 2023 worlds was divided on most things, with a sizeable minority believing that the thousand-kilometre jumble of steel and extruded ceramic was an art form and the Razor's Edge, that long scar down its side, a statement about futility.

The hoppers were toys for the rich in worlds where such definitions had become meaningless, because poverty was an abstraction and hunger a life choice, like living dangerously, monogamy or dying of natural diseases.

That was the theory, anyway.

"You don't have the faintest idea what I'm talking about, do you?"

The small boy shook his head.

Of course he didn't. New emperors rarely did.

When Zaq awoke he was lying in sunlight and such was his fear of the unexpected brightness that he rolled straight off his bed and underneath a table, crouching in the safety of its shadow. Somehow the whole of Rip had revolved, so that the glassed-over rip within which Zaq's village squatted now faced a gap between the worlds above. Their village had become desirable overnight.

Eli had tousled his hair, let him play with the rat and laughed at him, and when that didn't work his mother sent Zaq to bed without supper. Since the shack had only one room, food was a rarity and what with there being no front door and holes in the roof and no one would be sleeping that night, this was more for show than anything else.

"Zaq..."

Morning came broken. And only the butterfly understood how Rip kept to its new orbit beyond the edge of the 2023 worlds, but then the butterfly knew why gravity still held long after the electricity was gone and most of the food boxes stopped producing food. There had been a systems failure on Rip forty-eight centuries earlier, four thousand eight hundred and three years to be exact.

"What?"

Zaq looked at his mother.

"Four-thousand-eight-hundred-and-three..." She said the words without understanding because the highest number Maria knew was twelve, which had been her age when she met Eli's father: A scavenger with scars older than she was and hard connections, the kind that paid him in knives, medicine and food.

After Gabriel had come Eddie, who traded metals for food.

"Scrap," Zaq said, looking at the apple she held.

"You miss Eddie?"

For Zaq the question was meaningless. Eddie had been with his mother for less than eighteen months, leaving one morning to strip copper from level fifteen of the Rip and that had been it, Eddie never returned. Zaq had absolutely no memory of the hard-eyed man who fathered him and how could he? It was six months after Eddie's disappearance before Maria began pulling afterbirth from between her legs, while Eli cut the cord and wiped slime from the new baby with his hands. This had been Zaq's introduction to life and many on Rip had introductions far worse.

"Four-thousand-eight-hundred-and-three," Zaq said, tasting the size of the number. It sounded like something the ghost mothers might say. "The day is gone, the night comes in and my baby is lost..." Zaq knew all about the ghost mothers. Eli knew many scary stories and they stuck to the inside of Zaq's head like flies to tar-paper.

"Here," Maria said. "This will make you feel better."

Across the hut, Eli froze. He was older than Zaq and had first choice of all the food. "Me," he said.

Three paces took the boy to where his brother sat with an old blanket pulled tight around him against the shivers. On Eli's shoulder sat the rat he'd rescued from a shaft off the lower levels. Null had fallen through a hole and been unable to scrabble out.

Maria hated the animal, but it was hard to scold Eli when he returned from most trips with a fistful of copper wire or a circuit tray which changed patterns every few seconds. She'd once swapped circuitry for enough slab meat to feed all three of them for a month.

"Me first," said Eli, his eyes fixed on the apple.

"There's enough for everybody," his mother said.

Maria was lying. A third of the apple was already rotten and most of what was left was mottled with bruising. She'd taken it as payment in the dark, realizing too late that the sticky sweetness on her fingers was a sign of corruption, not quality. Maria had never seen fruit before, but the man who gave it to her had sworn it would make her both clever and lucky.

The tiny bugs living in its flesh were guaranteed to change her whole life for the better. Of course, the man had said, she could always give it to one of her sons, say the younger. The man's voice had been soft when he said this, as sweet as ever Eddie's had been.