Her full pink lips quiver and form a lazy half-smile, and her eyes are half-shut. It is obvious she's enjoying her confinement; that she's viewing the situation as part of some kind of sex game. The pale contours of her soft young skin ripple with life, her hips snaking as she tries to rub herself against the sheets. She looks good, too – just as I remember her from our first meeting. Her hennaed hair is cut short and stylish, spiky at the top, and her face is a perfect oval, with prominent cheekbones that are dotted with a scattering of freckles. She has mischievous brown eyes that sparkle with the vibrancy of youth, and a model's aquiline nose, with an emerald stud in its left side.

Seeing her alive on the screen is like a hammer blow, and I feel my jaw tighten.

As I watch, there's the sound of the bedroom door opening off camera and someone coming in. Leah turns her head in the direction of the newcomer and her expression changes perceptibly, the lust replaced by a flicker of confusion. 'Tyler,' she says, addressing the person off camera, 'what are you doing? Why are you wearing that mask?' Her words are distorted on the film and sound tinny. There's a mumbled reply that I can't make out, then Leah's expression changes again, this time the confusion being replaced by a wide-eyed fear. 'What's that?' she asks, panicky now. 'Why have you got a knife? Tyler, tell me.'

I feel my head throbbing painfully as the person she's talking to finally appears, moving round the foot of the bed in profile to the camera. He's naked as well, but his head is completely covered by a black rubber bondage mask, and in his right hand he holds a long, wicked-looking, wide-bladed butcher's knife.