Hours of anxious searching followed before eventually we found it: sunless Eden, a solitary sentinel, slowly orbiting the galactic disc, one face always turned inwards, the other looking out into the abyss. On its surface were the faint blotches and splatters of light that we’d seen in the images that came back with the Defiant four centuries ago, when it limped home broken and crewless.

We were forty thousand lightyears away from anyone we knew. If we’d possessed a radio transmitter powerful enough to send a signal back to our friends on Earth, they wouldn’t just be dead by the time it reached them, their whole civilization would be dead. An ice age would have come and gone. Their bones, those that were left unpulverized, would be twice as old as the cave paintings at Lascaux.

Still in our tiny metal box, we travelled the slow way now, across ordinary space. More than a week passed before we finally fell into orbit round Eden. Then we climbed into our landing vehicle – our Flying Saucer – fired up its gravitational engine, and set its navigation system to return to the exact same spot on the planet’s surface where the Defiant ’s identical landing vehicle had descended.

And now, dazed, disoriented, exhausted, we stared out at a forest of strange, dark, leafless trees. For four generations my family had been working towards this moment, ever since my great-­grandmother first uncovered the hidden story of the Defiant ’s return, suppressed for so long by the Salvationist authorities. For four generations, we had been leading the global effort to reconstruct the starship and retrace its steps.

But here we finally were. We stared into that strange forest and saw, to our complete amazement, two human beings.

They were funny, wild little creatures, barefoot and bare-breasted, with nothing on them but rough bits of animal skin tied round their middles, and both had the most horrible facial deformities, like great jagged wounds that had destroyed the entire centres of their faces. But they were undoubtedly human all the same. And what was more, they were – they must be – my own distant cousins, descended as I was from a man and woman of Jamaican heritage who lived in London four centuries ago, in the time before the flood, and were the parents of the only woman from Earth to ever come to Eden.

For a few seconds we just looked at them and they squinted back at us through their fingers, their faces screwed up against the light.