You reach the foot of the stairs. Mrs Jamieson's white-haired head appears beyond the banister rails to your right, her face turning to you.

You swing round, seeing her start to react, mouth dropping. You already know what you're going to do, how you're going to play this, so you punch her, knocking her down. She collapses to the floor, making little flustered, bird-like noises. You hope you didn't hit her too hard. You haul her up and keep your hand over her mouth as you drag her upstairs.

You pin her on the divan base and stuff a handkerchief in her mouth using the handle of the Stanley knife, then pull a pair of her tights over her head, tie them round her neck and mouth and put her inside the old, heavy wardrobe in the main bedroom, pulling out the few clothes hanging there and handcuffing her to the rail. She whimpers and cries but the gag muffles everything. You pull the tights she's wearing down and tie her ankles together above her sensible brown brogues, then you close the wardrobe doors.

You sit on the divan base, pull off the mask and sit there, breathing hard and sweating. You cool off, then put the mask back on and open the door again. Mrs Jamieson stands, trembling, her eyes through the dark grey mesh of the tights looking bright and wide. You shut the door, then close the curtains in that bedroom and the one with the iron-frame bed.

Her husband arrives half an hour later, parking the car in the drive. He comes in by the front door and you're waiting behind the kitchen door as he walks through; you make a noise, he turns and you punch him, sending him clattering back against the kitchen cabinet, producing an avalanche of willow-pattern plates. He tries to get up so you hit him again. He's very old and you're quite surprised it takes two punches to lay him out, though he's still a decent weight.

You stuff a pair of his wife's panties in his mouth and do the same trick with the tights, over the head and tied round the neck, then drag him upstairs to the second bedroom. You can smell he's been drinking recently; G & Ts, probably. Some cigarette-smoke smell, too. You're sweating again by the time you get him onto the bed with the iron frame.

You tie him to the bed, face down. He's starting to come round. When he's secured, you take out the Stanley knife. He was carrying a light windcheater which you left in the kitchen and he's wearing a blue Pringle sweater with a knickerbockered golfer depicted on the front, a Marks & Spencer's check shirt and a light string vest. You cut his clothes off, flinging them into one corner. His fawn slacks scatter golf tees when you throw them aside; his socks are bright red, his Y-fronts white. His golf shoes are brown and white, heavily spiked and with elaborate tongues and tasselled laces.

You take off your day-pack. You get the pillows from the main bedroom and stuff them and those from this bed under the old man's torso, raising his body from the bed. He's making spluttering, shouting noises now and moving weakly. You use a couple of rolled-up blankets to bring his rump up further, then go back to the day-pack and sort out the things you'll need. He struggles, as though wrestling with a pinned, invisible opponent. He's making a noise like he's choking but you don't do anything yet. You take the top off the cream.

There's a spitting, hacking noise and he must get at least some of the gag out of his mouth because he splutters, "Stop this! Stop this, I say!" Not the gruff, home-counties voice you recall from the television; more high-pitched and strained, but that's hardly surprising in the circumstances. He sounds less frightened than you expected, though.

"Look," he says, in something more like his normal voice; deep and no-nonsense. "I don't know what you want, but just take it and get out; there's no need for this; no need at all." You squirt some of the cream onto the vibrator.

"I think you're making a mistake," he says, trying to twist his head round to see you. "Seriously. We don't live here; this is a holiday home. It's rented; there's nothing of value here at all." He struggles some more. You kneel on the bed behind him, inside the inverted V of his scrawny, varicosed legs. There are broken veins on his back and upper arms. His shanks look grey and withered; his buttocks are very pale, almost yellowish, and the skin on his thighs, below the level shorts would come to, has a grainy, mottled appearance; his balls hang like old fruit, surrounded by wiry grey hair.

His cock looks slightly engorged. That's interesting.

He feels you get up onto the bed and shouts, "Look! I don't think you know what you're doing. This is aggravated burglary, young man; you — ah!"

You've put the cream-smeared tip of the vibrator against his anus, grey-pink and pursed between his spread buttocks. The cream must feel cold. "What?" he shouts, voice muffled by the gag. "Stop! What d'you think you're doing?"

You start to work the creamy plastic dildo into him, twisting it from side to side and watching the skin round his anus stretch and whiten as the ivory-coloured plastic slides in; a thin collar of white cream builds up there.

"Ah! Ah! Stop! All right! I know what you're doing! I know what this is about! All right! So you know who I am; but this is no way to — ah! Ah! Stop! Stop! All right! You've made your point! Those women — look, all right, I may have said things I regretted later, but you weren't there! You didn't hear all the evidence! I did! You didn't hear the men who were accused! You couldn't form an opinion of their character! The same with the women! Ah! Ah! Ah! Stop! Please; you're hurting! You're hurting!"

You have the vibrator about a third of the way in, not quite up to its maximum girth. You press harder, pleased at how much grip the surgeon's gloves give you but half-wishing you could say something though you know you can't, which is a pity.

"Ah! Ah! Jesus Christ, for God's sake, man, are you trying to kill me? Look, I have money; I can — ah! Ah, you filthy bastard — " He moans and farts at the same time. You have to turn your head away from the smell, but you push the vibrator in further. You can hear seagulls crying outside, beyond the closed curtains.

"Stop, just stop this!" he shouts. "This isn't justice! You don't know all the facts about those cases! Some of them were dressed like whores, dammit! They'd let any man have them; they were no better than whores! Ah! Fuck, fuck, you filthy blackguard bastard! You filthy, fucking queer bastard! Ah!"

He pulls and bucks, rattling the bed and pulling the knotted sheet-strips tighter. "You bastard!" he splutters. "You'll pay for this! You won't get away with this! They'll catch you; they'll catch you and I'll make damn, fucking sure they give you a lesson in the cells you'll never forget! D'you hear me? Do you?"

You leave the vibrator in there and switch it on. He heaves and pulls again but it doesn't do any good. "Oh, for God's sake, man," he moans, "I'm seventy-six; what sort of monster are you?" He starts sobbing. "And my wife," he says, coughing. "What have you done with my wife?

You get off the bed and take out the little wooden box from the zipped pocket of your shell-suit, carefully slide the lid off and tease apart the nest of toilet tissue inside. The wad of tissue holds a tiny vial of blood and a needle; it's a dirty disposable syringe needle, a little thing barely a centimetre long with a cone of ribbed orange plastic at the end that would fit onto the body of the syringe.

You listen to him as he curses you and threatens you, and you are still unsure. You couldn't decide when you were planning this whether to infect him with HIV-positive blood or not; you couldn't make up your mind whether he really deserved it, and so you've left it until now to make your decision.

Sweat runs into your eyes as you stand there.