The smell of blood is sickening. Hundreds of carcasses hang from silver hooks, stiff, shiny with frosty blood. I know they're just animals - cows, pigs, sheep - but I keep thinking they're human.

I take a careful step forward. Powerful overhead lights mean it's bright as day. I have to tread carefully. Hide behind the dead animals. Move slowly. The floor's slippery with water and blood, which makes progress even trickier.

Ahead, I spot him... the vampire... Mr. Crepsley. He's moving as quietly as I am, eyes focused on the fat man a little way ahead.

The fat man. He's why I'm here in this ice-cold slaughterhouse. He's the human Mr. Crepsley intends to kill. He's the man I have to save.

The fat man pauses and checks one of the hanging slabs of meat. His cheeks are chubby and red. He's wearing clear plastic gloves. He pats the dead animal - the squeaky noise of the hook as the carcass swings puts my teeth on edge - then begins whistling. He starts to walk again. Mr. Crepsley follows. So do I.

Evra is somewhere far behind. I left him outside. No point in both of us risking our lives.

I pick up speed, moving slowly closer. Neither knows I'm here. If everything works out as planned, they won't know, not until Mr. Crepsley makes his move. Not until I'm forced to act.

The fat man stops again. Bends to examine something. I take a quick step back, afraid he'll spot me, but then I see Mr. Crepsley closing in. Damn! No time to hide. If this is the moment he's chosen to attack, I have to get nearer.

I spring forward several feet, risking being heard. Luckily Mr. Crepsley is entirely focused on the fat man.

I'm only three or four feet behind the vampire now. I bring up the long butcher's knife that I've been holding down by my side. My eyes are glued to Mr. Crepsley. I won't act until he does - I'll give him every chance to prove my terrible suspicions wrong - but the second I see him tensing to spring...

I take a firmer grip on the knife. I've been practicing my swipe all day. I know the exact point I want to hit. One quick cut across Mr. Crepsley's throat and that'll be that. No more vampire. One more carcass to add to the pile.

Long seconds slip by. I don't dare look to see what the fat man is studying. Is he ever going to rise?

Then it happens. The fat man struggles to his feet. Mr. Crepsley hisses. He gets ready to lunge. I position the knife and steady my nerves. The fat man's on his feet now. He hears something. Looks up at the ceiling - wrong way, idiot! - as Mr. Crepsley leaps. As the vampire jumps, so do I, screeching loudly, slashing at him with the knife, determined to kill...