'Your staff,' said Logan. 'Do they have access to the cars?

Out of hours?'

Mr Robinson licked his lips and said 'em…' a couple of times. 'The sales team are encouraged to drive the demonstrator models and study the manuals, so they can answer any questions.' He gave a sickly smile. 'It's all part of Wellington Executive Motors' commitment to-'

'The guy who delivered Neil Ritchie's car…' Logan checked his notebook for the name. 'Michael Dunbar – what does he drive?'

'He, em…' Round beads of sweat were prickling out on Robinson's shiny forehead. 'I'd have to check.'

'You do that. And while you're at it, I want to know every car he's had in the last two months. And I want to see his personnel records too.' Logan sat in one of the comfortable leather seats reserved for special customers and smiled as the beads of sweat on Mr Robinson's face started dribbling their way down his face and around his jowls. 'And yes, we'd love a cappuccino.'

According to the company's records, Michael Dunbar had been assigned a different car every week: Lexus, Porsche, Mercedes, but he was driving a silver BMW the week Skanky Agnes was assaulted. 'So,' said Logan, 'where is he today?'

Mr Robinson worried a hand through the strands of hair stretched across his bald crown. 'I just don't see how this can do any good. I mean, there's no way any of my staff-'

'Where is he?'

'He, erm… called in sick this morning: migraine.

Michael suffers from them now and then, ever since the divorce Logan scanned through the showroom timesheets for the last fortnight. 'Looks like he called in sick last Wednesday too.'

The day after Holly McEwan went missing, presumed dead.

'Another migraine?' Mr Robinson nodded. Logan double checked the sheet: every time a prostitute was abducted and killed, Michael Dunbar called in sick the next day. And today he was off with another migraine. That probably meant another dead body.

The radio is on in the garage, Classic FM playing Dido's Lament, Dame Janet Baker making every word hang in the air like a dying jewel. Humming along with the music, he packs away the vacuum cleaner's extendible hose and carries the machine back through into the house, returning it to the cupboard under the stairs. Ever since Tracy… Ever since THE DIVORCE, he has kept the house spotless. Not a thing out of place.

It's a big house – big enough for a husband, a wife and three children. Big enough to feel empty and hollow now that it's just him on his own. With a sigh he lays his forehead against the wall and closes his eyes, sharing the house's emptiness. Its sadness.

In the garage, the music swells to a close and then some crass advert for double-glazing blares out, spoiling the moment. Frowning, he goes back through and turns the radio down.

The car sitting in the middle of the garage is now as clean as the house: a shining, top-of-the-range BMW coupe, silver with black leather and walnut trim. Very stylish, and his for another three days. Then, maybe he'll try a Lexus, something with a lot of storage space? After all, this time it's been a bit of a squeeze. He closes the BMW's boot, making sure the plastic sheeting doesn't get caught in the lock. He'll go for a drive later, somewhere nice and secluded where no one will see him.

He takes one last look at the car before heading back into the house.

The cellar is bigger than it looks. Before THE DIVORCE this room was full of things: forgotten wedding presents, the children's old toys, shoeboxes full of photographs, bits of furniture Tracy inherited from her parents… But not any more. It all went when Tracy did. Now the basement is hollow and dead, swept twice a day, mopped every other day.

Cleanliness is important. Cleanliness is always important. After all, one wouldn't want to catch anything.

The doorbell goes and he looks up at the ceiling. Perhaps if he ignores it… But the doorbell sounds again, a cold and empty noise in a cold and empty house. He sighs, but does his trousers up. He can always come back. There's no rush.

He climbs back up the stairs to the hall, and locks the cellar door behind him as the doorbell chimes once more.

'All right, all right, I'm coming.' He walks down the hall, pausing to check his reflection in the mirror, putting on his migraine face, just in case it's someone from work, come to see if he needs anything. They're good that way. But when he opens the door – squinting painfully into the afternoon light like his head is splitting open – there's a man he doesn't know standing outside, dressed in a dark grey suit that would benefit from professional cleaning. A man he's sure he's seen somewhere before…

'Mr Dunbar?' says the man, with a cold smile, holding up some sort of ID card, 'DS McRae. Mind if we come in?'

They found the body in the boot of a spanking-new BMW, in Michael Dunbar's garage. It was a woman, naked, wrapped in clear plastic sheeting, her limbs stiff and cold. Her body battered and bruised. Her head wrapped in a blue plastic freezer bag.

'Christ,' said Rennie, reaching into the open car boot with a gloved hand, prodding the cold, pale skin through the clear plastic. 'She's rock solid Logan turned and stared at the muted figure of Michael Dunbar. He was an unassuming-looking man, late twenties to early thirties, in tan chinos and a denim shirt, both ironed to razor-creased perfection. Tidy haircut sitting above a slightly rectangular, clean-shaven face. Killer. 'Well, Mr Dunbar,' said Logan trying to keep the anger out of his voice. 'Care to explain why you've got a naked woman's corpse in the boot of your car?' Dunbar bit his lip and shook his head. 'I see,' said Logan. 'Well, guess what? Doesn't matter if you want to tell us or not. We've caught you red handed. Soon as we've finished searching the premises, we're all going down to the station. And you're going to get fingerprinted and DNA-sampled and then the forensic boys are going to tie you to the two other women you've killed.'

'You…' Dunbar's dinner-plate eyes slid from Logan's face across to the open boot of the car and its cold? dead contents. 'I… I don't want to go. I want to speak to a lawyer.'

I'll bet you bloody do.' Logan turned round to see DC Rennie, still staring into the car boot, with his mouth hanging open. 'Rennie, get on the phone – I want a duty doctor, pathologist and the PF over here, and I want them here now.' Rennie dragged his eyes from the woman's battered corpse and his mobile from his pocket as Logan marched their suspect out into the hall, where the noisy sounds of a search in progress rattled down from the upstairs rooms. Four uniformed officers from FHQ, turning the place upside down.

A banging at the front door, and a familiar dirty-grey moustache and its owner struggled into the hallway, carrying a large box of equipment. 'Where d'you want us?' Logan told him to start with the body in the garage, then pretended not to notice the line of white-boiler-suited technicians whistling Heigh-Ho, Heigh-Ho, It's Off To Work We Go as they trooped through the hall.

When the last grey box had been manhandled out of sight, Logan took a look around the bottom floor, dragging Michael Dunbar with him. Large lounge: festooned with photographs of Dunbar, a woman, and three children – two boys, one girl; spotless carpet and ornament-free mantelpiece.

The kitchen was similarly immaculate, big enough to accommodate a breakfast bar and a dining table. Utility room off the kitchen: upright freezer full of ready meals, dishwasher, sink, cupboards. There was one more door leading off the hall, but when Logan tried the handle it was locked.

'Where's this lead?' Dunbar wouldn't meet his eyes. Logan poked him in the chest. 'Give me your keys.'