I tried not to think about whatever emotions churned within those silvered carapaces, what despairing debates might chatter on invisible wavelengths. I was, after all, trying to complete a mission. And I had been exhausted even before I got back to Pael. I just kept going, ignoring my fatigue, focusing on the task.

I was surprised to find it was done.

We had made a sail hundreds of metres across, stitched together from the invisibly thin immature Ghost hide. It was roughly circular, and it was connected by a dozen lengths of fine rope to struts on the panel we had wrenched out of the wreck of the yacht. The sail lay across space, languid ripples crossing its glimmering surface.

Pael showed me how to work the thing. ‘Pull this rope, or this one . . .’ The great patchwork sail twitched in response to his commands. ‘I’ve set it so you shouldn’t have to try anything fancy, like tacking. The boat will just sail out, hopefully, to the cordon perimeter. If you need to lose the sail, just cut the ropes.’

I was taking in all this automatically. It made sense for both of us to know how to operate our little yacht. But then I started to pick up the subtext of what he was saying. You, not us.

He shoved me onto the deck panel, and pushed it away from the Ghost ship. His strength was surprising. He was left behind. It was over before I understood what he was doing.

I watched him recede. He clung wistfully to a bit of tangle.

The sail above me slowly billowed, filling up with the light of the brightening sun. Pael had designed his improvised craft well; the rigging lines were all taut, and I could see no rips or creases in the silvery fabric.

‘Where I grew up, the sky was full of sails . . .’ My suit could read Pael’s, as clear as day.

‘Why did you stay behind, Academician?’

‘You will go further and faster without my mass to haul. And besides - our lives are short enough; we should preserve the young. Don’t you think?’

I had no idea what he was talking about. Pael was much more valuable than I was; I was the one who should have been left behind. He had shamed himself.

Complex glyphs crisscrossed his suit. ‘Keep out of the direct sunlight. It is growing more intense, of course. That will help you . . .’ And then he ducked out of sight, back into the tangle.

I never saw him again.

The Ghost ship soon receded, closing over into its vast egg shape, the detail of the tangle becoming lost to my blurred vision. I clung to my bit of decking and sought shade.

Twelve hours later, I reached an invisible radius where the tactical beacon in my pocket started to howl with a whine that filled my headset. My suit’s auxiliary systems cut in and I found myself breathing fresh air.