"Doesn't matter," the first voice said. "We've got enough."

The snow had stopped burning Tris's feet. Her fingers felt normal. She no longer felt the need to clamp her hands between her legs or across her chest, hiding them in the darkness of her underarms. Even her smell was gone, that stink of bruised flesh and ripped pain.

"Damn," said a voice.

"You tell me," Luca said. He was sitting outside his bivouac, cupping his hands around a flame that leapt between his thumbs, like electricity arcing between points. Tris had just asked him why she was standing bootless in the snow.

He didn't seem that surprised to see her or that pleased either. "Knew you'd be back," he said, stuffing his hands in his pockets. "Where else could you go?"

Tris knew this was untrue and wanted to explain how difficult it had been to leave the tigers, how painful wrenching her hands from the flame of their fur, but she was too busy looking at Luca's face.

Someone had clawed ragged lines across his cheek, four gashes that ran from near his ear to the side of his chin. And to judge from the holes in the snow and the discarded pink-streaked, compacted handfuls of ice around his feet, Luca had been trying for some time to staunch the bleeding.

"The tigers attacked you?"

The Baron stared at her. He looked thinner than yesterday, which was thinner than the day before. His eyes were huge and his mouth twisted into something between anger and disgust. He seemed to be waiting for something.

"An apology would be good," he said at last.

"For what?"

"Oh." Luca shrugged. "I don't know... How about for trying to rip off half my face and disappearing into the wilderness for two hours?"

"Me?"

"Yeah," said Luca, "you." One hand went up to touch his face.

"It can't have been me," said Tris. "I wasn't even here."

"Yes, you were," said Luca. "And it was." Scooping up snow, he held it to his cheek and then tossed away the soiled handful. "You want to tell me why you did it?"

"I... wasn't... here." Tris left a gap between each word, just in case Luca needed time to digest their sense. "And," Tris added, speeding up, "if I wasn't here, then I couldn't have done it, could I?"

"So where were you?"

"With the snow tigers," said Tris. "I heard them breathing. And when I looked outside they were waiting for me. They were beautiful," she said. Tris wanted to say more but sadness had tightened her throat. She should have stayed with them, she knew that now.

The tigers were right.

Luca sighed. "Maybe you were having nightmares," he said.

Moss spiralled along the main cables where fat cords had been twisted together and weather-bleached ropes hummed in the wind that whistled along the canyon, keeping the suspension bridge mostly clear of snow.

Two rusting iron rings had been set into a rock-face behind Tris. What happened at the other end was impossible to say because everything but the first ten paces of the bridge was lost in a flurry of snow.

"I've heard of this," Luca told Tris.

It occurred in a story his father had told him. About the first ambassador from Luca's people to set out for the Forbidden City. He began the trip without permission from the Tsungli Yamen, the Bureau of Foreign Affairs. And having packed his family gods into a lacquer trunk and commanded his servants to carry himself and his wife in separate sedan chairs, he set out for the capital of the 2023 worlds, leaving Luca's father in charge of his affairs.

Luca's father never told his son exactly what happened, but over the years Luca came to understand that it was a disaster. The sedan chairs were found ripped apart in a ravine near the start of the plateau. A silk changfu belonging to the ambassador's wife was discovered two days later, tied to a pole like a flag and rammed into the snow.

That was all Luca's father ever said.

The original Baron Pacioli had hated the 2023 worlds. No one in the worlds did what they were told, because there was no one but the Library to tell them what to do and the Library never told, it merely suggested.

This had taken Luca's father most of his life to understand. No families were bound to other families. No groups depended for employment or shelter on the obligation of others. Indeed, Luca's father wasn't sure the concept of family even existed on most of the 2023 worlds in any sense he understood.

People lived, they were fed by the Library and they died when they wanted. No codes enforced dress or behaviour. Names, sexes, body shapes and relationships were fluid and all could be changed without attracting approbation.

And in the middle of this chaotic fluidity lived the Chuang Tzu, his every move subject not just to age-old rules and regulations but to intense interest and speculation from the 148 billion individuals Luca's father assumed the Emperor existed to govern.

Because there was the other problem. So far as Baron Pacioli could work out, the Emperor issued no laws and delivered no judgements, no one needed his permission to do anything. The throne was powerless, his importance apparently token. Unless, of course, that stuff about the weather was true and chaos was what the Emperor required from his subjects.

"Which world?" Luca asked, suddenly turning back to face Tris.

"What?"

They were at the edge of the chasm and the rope bridge disappeared into the blizzard ahead of them. Luca and Tris had been standing like this for some time.

"Which world are you from?" said Luca. "They all have names, don't they?" He'd known those names once, as a small child.

"We've been through this." The girl's voice was entirely matter-of-fact. "I don't come from a world."

"You must," Luca said. "Where else could you be from?"

"Heliconid," said Tris. "You won't have heard of it."

In the end it was Tris who stepped onto the bridge. She had Luca's rope tied around her waist and both thorn sticks strapped across her back. She had her blade drawn and held in her right hand. For some reason Luca found this hysterically funny, although he wouldn't tell her why.

Testing each plank before putting her weight on it meant it took Tris the best part of an hour to cover a distance she could have walked in five minutes at her normal speed. And when the blizzard cleared and the far end of the bridge remained resolutely out of sight, Tris agreed with Luca that they'd have to do it differently.

"Okay," she said, as she untied the rope knotted around her waist and handed it to Luca. "I need you to lengthen this." Tris didn't know how Luca would do it, she only knew he could.

"Much better," said Tris, when he returned the end to her.

Retying the rope around her waist, Tris tested the knot by yanking it as hard as she could. "We don't have time to check every step," Tris said, sounding more sure than she felt. "So I'm going to walk normally and you'll save me if I fall through. And if you fall through then I'll save you... Although that's not as likely."

Afterwards Tris came to believe that she'd walked the bridge for weeks, maybe months, suspended over a nothingness so deep that, even on the afternoons the snow cleared, she never saw the bottom.

In fact, it took less than three days. Seventy-two hours during which a final figure of ninety-eight billion people watched Tris slip into a mental state little higher than stupefaction. It was during the last of these days that Tris decided she would burn the Chuang Tzu's precious pavilions around his ears.

She didn't remember telling Luca this, although she remembered his answer. Which was that the idea probably acquired its all-encompassing appeal from the fact that she was dying of cold.

The sheer strangeness of Tris's journey was enough to make even those who scorned the feeds decide to make an exception. Rumour in the 2023 worlds was a strange beast, widely recognized and little understood, except by a few ancient mememagicians who studied more for the sake of study than from hope of surpassing the early masters.