‘And,’ Borno said coldly, ‘it’s in the hands of the Black Ghost.’

‘So we have to stop it,’ Hex said. The others nodded, determined.

‘All right,’ Hella said. ‘But how? We’re still stuck in this cave.’

‘We have to get off the planet,’ Hex said. ‘And as far as I know the only launch capabilities are the nightsiders’.’ She considered Swimmer. She wondered if he knew he had been projected into the farthest future of his own kind. ‘Hella, do you think your new friend could help us get across the terminator?’

V

Under the guidance of Swimmer-with-Somethings, they journeyed north. They would cross into night somewhere near the planet’s spin pole.

The journey took them days - Earth days. They travelled out of sight of the ur-Ghosts, as they took to calling them, these cousins of Swimmer hardened for space but not yet of the optimal spherical form they would reach later. They clambered through tunnels, along the shadowed floors of deep ravines, and swam under the sea, their suits’ inertial control packs labouring to keep up with Swimmer’s economical motions. When they stopped, while the humans tended their blisters, Swimmer huddled in a gelatinous mass in any sunlight he could find, or, if they were in the ocean, he discorporated with exuberant relief. It was a mystery to Hex how the little shrimps and algae and amphibians that made up his body knew when to come back, and how to reintegrate.

As they forged steadily north the sun slid down the sky, and the shadows stretched long and deep. In the dimming sky Hex glimpsed stars, and the single bright pinpoint, steadily tracking, that was the Black Ghost’s habitat.

At last they came to a place where the sun sat on the horizon, glowing like hot coal. It looked as if it was about to set, but of course it never would. Life was sparse at this high latitude. An analogue of grass spread across the ground, though its native photosynthetic chemicals made it black, not green. But nothing grew in the long shadows, on this world where every shade was permanent.

Swimmer left them here. Unable to tolerate freezing temperatures, he could go no further. ‘Fight well for me,’ he said to them through Hella’s translator box. Then he squirmed away, like rainwater disappearing down a drain.

Hex looked north into the darkness. She saw motion: palette-ships, patrolling this boundary between day and night.

Borno pointed. ‘There are structures over that way.’

‘Let’s get on with it,’ Hella said tautly.

Following Borno’s lead, they walked into the night. Hex could sense Jul’s fear, Hella’s tension, and Borno’s grim, bloody determination.