They led him into the city, away from the canal. They walked with a sound of rustling clothes, even of boots crunching on the scattered sand. But of the four of them only Symat left footprints.

‘We saw you breaking the windows,’ Tod said. ‘Why did you do that?’

‘Why not?’

Tod considered. ‘It’s wrong to break things.’

‘But nobody’s coming back here. People are leaving the planet altogether. What difference does it make?’

‘My parents are coming back,’ Chem said.

Mela said softly, ‘Chem—’

‘I wouldn’t throw stones,’ the boy said. ‘My parents wouldn’t like it.’

‘What parents? . . . You couldn’t throw stones anyway,’ Symat said. ‘You’re a Virtual.’

That seemed to hurt the boy, and he glanced away.

Mela was slim, thoughtful, grave. She didn’t react to this exchange one way or another. But somehow she made Symat feel ashamed of upsetting the Virtual boy.

They came to a building, an unprepossessing block in a neighbourhood of crystalline spires. It was as unlit as the others. ‘There’s food in here,’ Tod insisted. ‘Through that door.’ They stood waiting for him to open the door.

‘Why don’t you go in? You’re Virtuals. You could just walk through the wall.’

Mela said, ‘Protocol violations. We aren’t supposed to.’

‘It hurts,’ Chem said.

Symat said, ‘I haven’t been around Virtuals much.’ He stepped forward, pushed at the door’s polished surface, and it slid open.

The building was an apartment block. They wandered through suites of rooms. Heavy furniture remained, chairs and tables and beds, but smaller items had been taken away.

‘I’ve seen people take stuff,’ Symat said. ‘Clothes and ornaments and toys, even sets of plates to eat dinner. They carry them in suitcases and boxes when they go through.’

Mela asked, ‘Through where?’

‘Through the transfer booths. Imagine carrying plates and forks and knives into another universe!’

‘What are they supposed to take?’ Mela asked reasonably.

They came to a kind of kitchen, where a nanofood replicator was still functioning. Symat asked it to prepare him something warm, and soon rich smells filled the air.

‘It probably needs restocking,’ Mela said. ‘You can scrape up some algae from the canal, I guess.’

Chem said sharply, ‘If you can keep from getting stuck!’ He and Tod laughed.

Mela reproved the boys. Symat sat at a table and ate in dogged silence. The Virtuals stood around the table, watching him.

Chem said, ’Of course you won’t have to put more glop in the nanofood box if your parents come for you.’

‘They won’t come,’ Symat said, chewing. Mela watched him with that quiet gravity, and he felt impelled to add, ‘They don’t know I’m here.’

‘Are you hiding?’ Chem asked. ‘Did you run away?’

‘Did you do something wrong?’ Tod asked, wide-eyed.

‘They want me to go into a transfer booth with them. I don’t want to go.’

Chem said, ‘Why not?’