The sun disappeared altogether. They passed a few last trees, so tall that their leaves blazed in sunlight while frost gathered on their roots. ‘Interesting bit of biomechanics,’ Jul said nervously. ‘They must have evolved to exploit the temperature differences between their crowns and their roots. And I guess these last trees must be as tall as this stock can grow, otherwise—’

‘Shut up,’ Borno hissed.

They came to a wall. It was just a heap of what looked like sandbags, glowing silvery in the dim light. They crouched behind this and cautiously peered at the structures that lay beyond.

Hex saw a kind of city, spun out of silver and ice, resting on a black velvet landscape. Necklaces swooped between cool globes, frosted, icicles dangling. Sparks of light drifted between silvered domes: Ghosts, or ur-Ghosts. The place had an organic look, as if it had been grown here rather than planned. But there was nothing of Swimmer’s vibrant, swarming physicality to be seen in this chill place.

This was a typical Ghost colony. Ghosts stayed away from the heat of stars, but they had remained planet-dwellers; they tapped a world’s geothermal heat for their energy, just as they evidently had on this, their own freezing world. And their colonies always had this tangled, unplanned look.

There were anomalies, though. On a slim spire that towered over the reef-city, a light pulsed steadily, brilliant electric blue. And at the very centre of the township a squat cylinder brooded. Hex’s suit sensors told her this was merely the upper level of a complex dug deep into the ground, where thousands of Ghosts swarmed. This fortress, very unlike Ghost architecture, was the work of the Black Ghost, obvious even here, just inside the boundary of night.

Borno tapped Hex on the shoulder and pointed.

A handful of ur-Ghosts swarmed around a palette-ship on the ground. The Ghosts’ forms were variants of parallelepipeds, like slanted boxes. They were really quite beautiful, Hex thought, their facets flashing like mirrors in the starlight as they worked.

Borno whispered, ‘Four of them, four of us. We can take them out. And then we can grab that palette-ship and get to orbit.’

Jul hissed, ‘We only just crossed the terminator. Maybe we should go further before—’

‘What’s the point? We came here to find a way off the planet. There’s our opportunity.’ He raised his hand, holding a knife.

Hex said, ‘Borno is right. The longer we hang around the more chance we have of getting caught. Let’s do this. There’s a blind side over there, to their right. Borno, if you take Jul and head that way, Hella and I can—’

Hella cried, ‘Look out!’