On the outskirts of the Conurbation there was a broad pit scooped out of the ground, its crudely scraped walls denoting its origin as post-Occupation: human, not Qax. In this pit rested a number of silvery, insectile forms, and as the flitter fell further through the sunlit air, Hama could see people moving around the gleaming shapes, talking, working. The pit was a shipyard, operated by and for humans, who were slowly rediscovering yet another lost art; for no human engineer had built a spacecraft on Earth for three hundred years.

Hama pressed his face to the window - like a child, he knew, reinforcing Nomi’s preconception of him - but to Lethe with self-consciousness. ‘One of those ships is going to take us to Callisto. Imagine it, Nomi - a moon of Jupiter!’

But Nomi scowled. ‘Just remember why we’re going there: to hunt out jasofts - criminals and collaborators. It will be a grim business, Hama, no matter how pretty the scenery.’

The flitter slid easily through the final phases of its descent, and the domes of the Conurbation loomed around them.

There was a voice, talking fast, almost babbling.

‘There is no time. There is no space. We live in a universe of static shapes. Do you see? Imagine a grain of dust that represents all the particles in our universe, frozen in time. Imagine a stupendous number of such dust grains, representing all the possible shapes the particles can take. This is reality dust, a dust of the Nows. And each grain is an instant, in a possible history of the universe.’ A snapping of fingers. ‘There. There. There. Each moment, each juggling of the particles, a new grain. The reality dust contains all the arrangements of matter there could ever be. Reality dust is an image of eternity . . .’

She lay there, face pressed into the dirt, wishing none of this was happening.

Hands grabbed her, by shoulder and hip. She was dragged, flipped over on her back. The sky above was dazzling bright.

A face loomed, silhouetted. She saw a hairless scalp, no eyebrows or lashes. The face itself was rounded, smoothed over, as if unformed. But she had a strong impression of great age.

‘This won’t hurt,’ she whispered, terrified. ‘Close your eyes.’

The face loomed closer. ‘Nothing here is real.’ The voice was harsh, without inflection. A man? ‘Not even the dust.’

‘Reality dust,’ she murmured.

‘Yes. Yes! It is reality dust. If you live, remember that.’

The face receded, turning away.

She tried to sit up. She pressed her hands into the loose dust, crushing low, crumbling structures, like the tunnels of worms. She glimpsed a flat horizon, a black, oily sea, forest-covered hills. She was on a beach of silvery, dusty sand. The sky was a glowing dome. The air was full of mist; she couldn’t see far in any direction, as if she were trapped in a glowing bubble.