Through the jargon, I tried to figure out what this meant. ‘Something is using the dark matter? . . . Or are there life forms in the dark matter? And what does that have to do with the Xeelee, and the problems here on Shade?’

His face twisted. ‘I haven’t figured out the links yet. There’s a lot of history. I need my data desk,’ he said plaintively.

I pulled my chin, thinking of the bigger picture. ‘Academician, you’re on an assignment for the Admiral. Do you think you’re finding what he wants to hear?’

He eyed me carefully. ‘The Admiral is part of a faction within the Navy that is keen to go to war with the Xeelee - if necessary, even to provoke conflict. Some call them extremists. Kard’s actions have to be seen in this light.’

Actually I’d heard such rumours, but I stiffened. ‘He’s my commanding officer. That’s all that matters.’

Tilo sighed. ‘I understand. But—’

‘Lethe,’ Lian said suddenly. ‘Sorry, sir. But that mud is moving fast.’

So it was, I saw.

The mud was filling up the valley, rising rapidly, even as it flowed towards us. It was piling up behind a front that was held back by its own viscosity. As it surged forward the mud ripped away the land’s green coat to reveal bare rock, and was visibly eating away at the walls of the valley itself. Overlaying the crack of tree trunks and the clatter of rock there was a noise like the feet of a vast running crowd, and a sour, sulphurous smell hit me.

The gush out of the mountain’s side showed no signs of abating. That front was already tens of metres high, and would soon reach the village.

‘I can’t believe how fast this stuff is rising,’ I said to Tilo. ‘The volume you’d need to fill up a valley like this—’

‘You and I are used to spacecraft, Lieutenant,’ Tilo said. ‘The dimensions of human engineering. Planets are big. And when they turn against you—’

‘We can still get you out of here. With our suits we can get you over that bridge and to the transport.’

‘What about the villagers?’

I was aware of the woman, Doel, standing beside me silently, just waiting. Which, of course, made me feel worse than if she’d yelled and begged.

There was a scream. We looked down the ridge and saw that the mud had already reached the village’s lower buildings. A young couple with a kid were standing on the roof of a low hut, about to get cut off.

Lian said, ‘Sir? Your orders?’

I waited one more heartbeat, as the mud began to wash over that hut’s porch.

‘Lethe, Lethe.’ I ran down the ridge until I hit the mud.