Luca didn’t feel able to reply. The world was like a watery Earth, he thought, with a world-ocean marked by tiny ice caps at the poles and a scatter of dark brown islands. He felt unexpectedly nostalgic.

Dolo was watching his face. ‘Remember, though you are a Novice, you represent the Commission. We are the ultimate source of strength for these people. Keep your fear for the privacy of your quarters.’

‘I understand my duty, sir.’

‘Good.’

The yacht slid neatly into the world’s thick air. Under a cloud-littered blue sky the ocean opened out into a blue-grey sheet that receded to a misty horizon.

The yacht hovered over the largest archipelago, a jumble of islands formed from ancient and overlapping volcanic caldera, and settled to the ground. It landed in a Navy compound, a large complex marked out in bright Navy green and surrounded by a tall fence. Beyond the fence, the rocky land rolled away, unmodified save for snaking roads and scattered farms and small villages.

Luca and Dolo joined a handful of troopers in an open-top skimmer. Hovering a couple of metres above the ground the skimmer shot across the Navy compound - Luca glimpsed bubble domes, unpressurised huts, neat piles of equipment - and then slid through a dilating entrance in the outer wall and hurtled over the countryside.

They had to wear face masks. Even after twenty thousand years of terraforming of this world, there was still not enough oxygen in the air; it had taken half that time just to exterminate most of the native life. But they could leave their skinsuits behind, and Luca welcomed the feeling of sunlight on his exposed skin.

Dolo said, over the wind noise, ‘What you’re going to see is where many of those troopers you envy come from.’

Luca said, ‘I imagined birthing centres.’ Like the one into which he had been born, on Earth.

‘Yes. The children of soldiers are incubated in such places. But you’ve seen yourself that there is a - drift - in such populations, under the relentless selection pressure of combat. It’s a good idea to freshen up the gene pool with infusions of wild stock.’

‘Wild? Commissary, what is a “press gang”?’

‘You’ll see.’

The skimmer arrived at a village by the coast.

Luca stepped out of the hovering vehicle. The volcanic rock felt lumpy through the thin soles of his boots. A harbour, a rough crescent shape, had been blasted into the rock, and small boats bobbed languidly on oily water. Even through the filters in his mask Luca could smell the intense salt of the sea air, and the electric tang of ozone. But the volcanic rock was predominantly black, as were the pebbles and sand, and the water looked eerily dark.