By then they were under the shoulder of the Tract itself, tumbling down a thirty-light-year well between high temperature gas clouds. Soon, Galt & Cole’s big score filled the screens, not quite a planet, not quite a machine: a geological madhouse with aspects of both, having the gravitational signature of a low density rubble pile but eye-watering Mohr-Coloumb figures. It was as porous as sponge yet nothing could pull it apart. The highly cratered surface sported a uniform orange colour, slightly too pale for rust. Across it roiled deep cobalt shadows and strange-looking rivers of dust.

‘Home again,’ Gaines said.

‘Keep watching the skies, Carlo,’ he called as they left the ship.

‘These days there’s no need to run the maze,’ he told the assistant. But he took her in anyway. Some part of him still needed to show it off.

Back at the beginning it had been a fracturing, disconnective experience, a space flickering with bad light and worse topology. The tunnels, small-bore and intricately turned one moment, would become huge and simple the next; as full of generated sounds as they were echoes, with no way of telling which was which. ‘Worse,’ Gaines told the assistant as he led her along, ‘they changed their nature.’ One moment they were tiled with shiny ceramics, next some sort of organic-looking fibre was matted over everything. You could be in a blood vessel or waiting for a train, or feel yourself running like a fluid between glass plates: it was an archaeology from which anything could be intuited and of which nothing was true. ‘It wasn’t so much what you might find round the next corner,’ Gaines said, ‘as that you were round the next corner before you knew it was there.’ As a result – at the start, anyway – the maze had seemed more like a condition than a system. Its objects had seemed abstract.

‘What’s this I’m walking in?’ the assistant said.

Gaines stopped. ‘It’s water. It’s just water.’

He looked down uncertainly.

‘These are the safe parts,’ he said. ‘Back in the day, entire sections would go missing. They’d be one thing when you lost them, another when you found them again. In circumstances like that, you have to understand that your perception is what’s fragmentary, not the space itself. At some level an organising principle exists, but you will never have any confirmation of it. It will always be unavailable to you. Then, just as everyone’s stopped trusting themselves, someone finds their way through a trap, the expedition gets a little further in.’ All expeditions, he told her, failed in some way, but they each had a character of their own: and if, for a while, that character seemed like the reality of the explored space, it was the best you could expect. ‘You learn to work with it. We were total colonialists. Always on the back foot. Always in the thin slice of the present.