I dodged down the side of the old barn, hunting for a way in. Halfway down, almost hidden by a clump of nettles and ragwort, was a low wooden door, frail and rickety-looking with gaps between its shrunken planks and a space at the bottom where the wind whistled through. A kid might have wriggled through that gap, but not me. I tried the rusty doorknob and it rattled loosely. I shoved the door with my shoulder, once, twice, and it gave, pitching me forwards into the murky interior. Slamming it shut it behind me, I collapsed against it, relief flooding over me like cold water. My heart was thumping, trying to burst out of my chest. I took in a deep breath.

It was almost dark inside the workshop. I stood, breathing hard, waiting for my eyes to adjust to the gloom. Where was Vlad now? The big metal door in the adjacent shed rattled and I swore softly. He was closer than I thought. I felt for the lock on the little door behind me. My fingers found the cold metal of a lock-plate and the draught through the keyhole. There was no key. I slid my hand up and down the wood, my fingers searching, but there were no bolts either, no way of securing the door against outside. And soon Vlad would find it, as I had.

I grabbed the nearest chair from a stack of old furniture and rammed it under the door handle; it wouldn’t hold out against an assault for long, but it might buy me a few minutes.

Crossing the workshop on tiptoe, I opened the door of the tank room. I could just make out the shape of the big caustic tank. Above it hung the grid for lowering furniture, and above that, the skylight, one window open to the sky. If I could get up on to that grid, I might be able to squirm out through the skylight and on to the roof. The lid of the tank was shut and if I stood on it, I could probably reach the grid, haul myself up.

I closed the tank-room door, lifted a chair and set it down quietly next to the tank. As I stood on it, I heard a banging against the wooden door in the workshop. Vlad was trying to get in, throwing his body against it. I stepped up on the lid, feeling it flex slightly with my weight. Inside the tank I sensed the slightest movement as the body of lethal liquid shifted, and prayed that the lid would hold. I reached up with both arms. There was a crash as the little door to the workshop shattered, the scrape of the chair as it slid across the stone floor. I stretched up for the bars of the grid, standing on tiptoe, and my fingers closed around the cold metal bars. It rocked and the chains that supported it jangled.