I wandered through the deserted streets, barely able to stand the smell of death and rot, before I made my way back to the farmhouse, high on its hill.

I searched the whole place, from top to bottom, until I found a plastic tray containing four ampoules identical to the one Marlon had used on me. If there was any chance whatsoever Alice was still alive, I knew I had to find her and inject her with it.

From a bedroom I grabbed a clean change of clothes that more or less fitted, and took the car keys from Herschel’s still-cooling fingers. I had wondered if perhaps there had been others working here apart from Marlon and Herschel, but as I searched the house, I became convinced that they had been working here alone – although that did not preclude the possibility of other Red Harvest groups, in other parts of the world, working in similar secrecy.

I drove the car as far as I could before the sheer number of empty vehicles scattered across the roads forced me to abandon it for a motorbike with a full tank.

It took me another two days to reach London, during which I found no one alive. I had acquired a hunting-rifle from a sporting goods shop, having become concerned over the packs of increasingly feral dogs I was encountering. On my way through Ealing, I nearly came off my bike when someone, somewhere, started shooting at me, and I was forced to take a lengthy diversion before I could reach home. I don’t know what happened to that person, but I strongly suspect they didn’t survive much longer.

And then, at last, I arrived home, and looked down at Alice, her face strangely peaceful in death. I sat there by the side of our bed and wept until the sun rose above city streets that were silent for the first time in over a thousand years.

I buried Alice in our garden, the air full of the stink of putrefaction from the neighbouring houses. Then I left forever, making my way back to Oxford, and back to the basement where my new life had been born. There were computers there, and my hope was that they would contain information that might help me understand how Marlon and Herschel had carried out their act of genocide. If anyone else was alive out there in the rest of the world, they were going to need the antidote that had saved my own life.

But first, I wanted to see whether it might be possible to synthesize more than the pitiful four ampoules that remained in my possession.