The knife suddenly appeared right in front of my face as he jumped on my back and I was flung forward, tumbling down the steps, doing a somersault, smacking my head painfully on the hard linoleum steps. I knew that any moment I was going to be stabbed. But then I heard the knife clatter against the wall as he was thrown clear.

He landed hard against the wall at the bottom of the steps but somehow he still had the weapon in his hands, and now he was in front of me and blocking my way while I was lying on my stomach on the steps, only five feet from the tip of his blade. His face was bleeding where I'd cut him with the soap dish and his wiry hair was slightly askew. But he still wore the cruel, predatory smile as if it had been etched permanently on the stretched skin, and the expression in his eyes was one of chilling confidence, as if he knew that whatever I did it would make no difference because, in the end, the outcome was inevitable.

But I wasn't finished yet. I used my hands to push me upright as if I was doing some kind of springing press-up. Somehow I managed the process slightly quicker than him, before vaulting over the banister on to the next set of steps, stumbling down them, ignoring the savage pounding in my head.

Once again he was right there with me, and I knew he wasn't going to give up, so, summoning up every last ounce of whatever feeble reserves of energy I had left, I jumped the whole of the next staircase in one, landed hard on my feet, swung round using the banister as support, and did the same thing on the next one, and the next, feeling a kind of delirious adrenalin-fuelled excitement at the prospect of escape.

And at that exact same moment the stairs stopped and I realized I'd missed the ground floor, and possible safety. Instead, I was in the basement.