Then it hit me. Sometime in the next few days, or maybe even sooner, I would be next. They had, after all, been unable to extract any information from me whatsoever.

Later that night I somehow got one arm free of the thick tape securing me to my chair. They had been feeding me sporadically at best, and by now I had lost so much weight I was able to wriggle free of my improvised restraints, although I nearly dislocated a shoulder in the process. I made my way through the doorway, noting that Floyd’s body was gone. The airlock had been dismantled. I climbed the steps only to find the basement door locked.

I retreated into the shadows beneath the steps and waited a few hours, until I heard the jangle of keys. I had found a hammer lying on a workbench, and when Marlon came down the steps, I stepped out of the shadows, swinging it at his head.

He collapsed to the ground without a sound, his legs folding beneath him. I kept swinging the hammer, lost to blind fury and half-crazed from torture and the terror of my impending death. I recall little of what happened next, except that I found myself staring down at the pulped ruin of Marlon’s head, unable at first to connect that terrible sight with the bloody hammer still gripped in one hand. Before that moment, I would never have believed I was capable of such awful violence.

I searched his body, finding a pistol tucked into his belt. I ran upstairs with the gun in my hand just as Herschel stepped in through the front door. He barely had time to look up and open his mouth before I shot him in the head, the contents of his skull spattering against the door behind him.

I found Herschel’s mobile phone and tried to call Alice, but there was no signal. It was the same with the landline in the kitchen; when I picked it up, all I heard was a hiss of static, and not even a dialling tone.

Then I glanced up and saw a calendar with days crossed out hanging on the wall, and realized I had been held captive for very nearly a whole fortnight. I stared at the date, hardly able to believe it could have been so long, then searched around until I found some stale bread in a cupboard, stuffing it into my mouth until I retched and nearly passed out.

A little while later I made my way along the road on foot, through drizzling rain, until I reached the outskirts of Oxford. Everywhere I went I saw nothing but corpses, shrouded by great buzzing clouds of flies. I remembered the ampoule with which Marlon had injected me, and how I had recovered from a desperate and inexplicable illness in a matter of hours.