'You… you can't do this! I want a lawyer. You can't come in here and do this. This is my home!'

'Yes I can: I have a warrant.' Rachael Tulloch had rushed it through in record-breaking time. 'Now give me your keys.' 1… I don't feel well, I need to lie down 'Give me the bloody keys!'

With trembling hands, Dunbar pulled out a gleaming bunch of keys. Logan snatched them, trying one after another in the sturdy Yale lock until the thing went 'click' and the door swung open. A flight of wooden steps disappeared down into the darkness. Logan flicked the light switch and a dim glow filled the area at the bottom of the stairs.

'Rennie!' he shouted back into the garage and the constable came trotting out, still clutching his mobile phone to his ear, telling whoever it was on the other end that they needed the pathologist now, not next week. Logan pushed Dunbar at the constable.

'What you want me to do with him?'

'Buy him dinner and take him dancing. What the hell do you think I want you to do with him? Hold on to him!'

Logan turned and headed down the steps, already feeling guilty about snapping at the constable. He stopped, apologized and told Rennie he could come too, just as long as he kept hold of Dunbar and didn't let him accidentally fall down the stairs.

The basement steps were enclosed on either side with plasterboard and rough lengths of timber, thick ribbons of grey wire looping across the ceiling between the exposed joists.

And then Logan stepped out into the cellar proper, plastic sheeting scrunching beneath his shoes, and saw what was down there. 'Oh shit.'

Rennie: 'What? What is it?'

Dunbar: 'I really don't feel well! I have to go lie down Clear plastic sheeting covered the floor, sparkling in the light from the bare bulb like ripples on the surface of a dark lake. It was all the way up the far wall as well, held in place by reams and reams of silver duct tape. Ensuring the crumpled, naked woman – lying on her back with her legs spread at twenty past six, pale skin covered in purple-yellow bruises, face unrecognizably swollen and bloody, arms tied together above her head, fixed to the wall with a six-inch bolt – left no stains.

She wasn't moving.

A scuffling sound behind him and sudden intake of breath – that would be Rennie – then Dunbar said again, 'I… I'm really not feeling well…'

Logan grabbed him by the collar and rushed him backwards, crashing the man against the bare brick wall. 'You sick, twisted piece of shit!' Dunbar's eyes went wide, fear sparking from the edges, and Logan froze. He let go of the man's shirt and backed away. Dunbar wasn't worth it.

He wasn't worth it… But Logan seriously wanted to beat the living hell out of him.

Trembling with the effort, he turned and inched his way across the plastic sheeting, feeling it shift and slither beneath his feet as he picked his way carefully to the battered body, trying not to stand in any evidence. As First Attending Officer it was his responsibility to make sure the victim wasn't in need of medical assistance, even though it was bloody obvious she was dead. Christ, she looked as if she'd been run over by a combine harvester. There wasn't an inch of her that wasn't covered with a bruise or contusion. Maybe it was time for Michael Dunbar to fall down the stairs after all. Grimacing, Logan snapped on a fresh pair of latex gloves and squatted down beside the body, peering at the ruined face, trying to match the battered mess with any of the women he'd seen prowling the red light district, offering a good time in exchange for cold hard cash. Instead of which she'd got a cold hard death at the hands of-

A bubble of blood swelled and popped between her swollen lips. She was still alive!

Interview room four had an unwashed smell about it that seemed to make Michael Dunbar very uncomfortable.

He sat on the edge of his seat, obviously trying not to fidget, while Logan made DC Rennie do the tapes and introduction bit. They'd dragged Dunbar back to the station, processed him and got him into an interview room without having to talk to DI Steel: according to Big Gary she was still going at it with Clair Pirie and didn't want to be disturbed. This was followed by a leering, 'if you know what I mean…' Which meant that technically Logan was still in charge.

'So, Michael, or can I call you Mikey?' said Logan, settling back in his seat.

'Michael. Please. Michael. Not Mikey.'

'OK, Michael it is then.' Logan smiled at him. 'Why don't you tell us all about the two women we found in your house today? You can start with the one who's still alive if you like?'

'I have no idea what you're talking about,' said Dunbar, staring dully at the tape recorder, watching the spindles go round and round behind the glass.

'Don't be stupid, Michael: we found them in your house!

You were there remember?'

He took a long, shuddering breath. 'I really don't feel well.'

'Yeah? Well the duty doctor says there's nothing wrong with you. Not like the poor cow we pulled out of your basement – fractured skull, broken arms, legs, ribs, fingers, internal bleeding… feel free to jump in any time.'

'She was having an affair.' The words came out in a flat monotone. 'She…' He closed his eyes and took a deep breath, holding it in, then letting it out in a long, shivering breath. 'His name was Kevin and he was a chartered accountant. I… I come home one evening and they're SCREWING in our bed, while the kids are downstairs watching Sponge Bob Square Pants… Didn't even know I was there.' A bitter laugh that ended in a tear being wiped away. 'So I got my revenge: went out, picked up some ugly tart down the docks and fucked her.

Then I went home and fucked Tracy. Just like he'd fucked her…'

'But she found out, dMn't she?'

Another bitter laugh. 'Three days later my dick starts weeping yellow pus and I'm pissing barbed wire. Course she caught it too. And so did darling Kevin.' This time the laugh was more genuine. 'That'll teach the cheating bastard!'

Dunbar paused, watching the tape go round in silence. 'She left me. Took the kids and all her stuff and walked out the door…'

Logan pulled out a sheaf of photographs, propping one up against the tape recorder directly in front of Dunbar: a naked woman, lying on her back in the middle of a dark alley. 'Tell me about Rosie Williams.' Dunbar moved so he wouldn't have to look at the battered body any more, but Logan stuck another picture in front of him. A naked woman lying on her side on the damp forest floor. 'No? How about Michelle Wood?' Another photograph: wrapped in clear plastic in the boot of a car. 'Or Holly McEwan? No? How about this one?'

A battered face, covered in blood, the photograph taken an hour ago while they'd waited for the ambulance to turn up.

The final picture was a mugshot from the station's collection:

Skanky Agnes Walker, full face and side on. Dunbar stiffened.

Logan tapped the print with his finger. 'She was the first wasn't she?'

'Dirty bitch…' they were barely words.

A long silent pause, only broken by the dull whir of the lape machine and someone's shoes squeaking on the linoleum in the corridor outside.

'Tiffany. The one in the cellar. She said her name was Tiffany. Picked her up last night in a shiny new car and took her out to Balmedie beach.' A small smile played around his lips as he relived the memory. 'Paid her to suck my cock and when she was finished – smacked her over the back of the head with a hammer. Bundled her into the boot. Took her home. Dragged her down to the basement and tied her up. Couldn't have timed it better, 'cos you know what?' He leant forward and whispered the words.

The last one was dead.'