They couriered the X-rays straight over to the morgue and ten minutes later Doc Fraser confirmed the identification:

Graham Kennedy was now officially dead. The enquiry finally had somewhere to start.

Insch grabbed PC Steve and told him to go get everything Records had on Graham Kennedy and meet them in the car park, then bellowed for a DS Beattie to get his backside in gear: they were going to break the news to Graham Kennedy's next of kin. And have a bit of a rummage through his things.

'Er, sir,' said Logan following in the inspector's wake, 'I kinda hoped I could come with you on the shout?'

Insch raised an eyebrow and mashed the lift button with a fat finger. 'Oh aye? And what about DI Steel?

You're supposed to be working for her. "More immediate supervision", remember?'

Logan opened and closed his mouth. 'Come on, sir! I didn't ask to be transferred! And anyway, it's my day off.

I've-'

'You've got a day off and you want to go on a shout?'

Insch looked at him suspiciously. 'You gone mental or something?'

'Please, sir. I need to get out of Steel's team. It's driving me mad! Nothing gets done by the book: even if we do get a result, it's going to be so tainted any defence lawyer worth half a fart will tear it to shreds! If I don't get some sort of success under my belt, I'm going to be stuck there till they fire me, or I go completely off my head.'

Insch shook his head, a small smile on his face. 'I hate to see a grown man beg.' A puffing, bearded detective sergeant appeared at the end of the corridor, dragging on a huge, multicoloured weatherproof jacket. DI Insch waited until he'd run the length of the corridor and come to a screeching halt in front of them, before telling him he wasn't needed after all. He'd be taking DS McRae along instead.

Swearing quietly, the bearded bloke slouched back the way he'd come.

The inspector grinned. 'Just like to see the fat wee bugger run for his money,' he said happily. Logan knew better than to say anything about pots and kettles.

As they marched downstairs to the car park, Insch quizzed him on DI Steel's cases, wanting to know everything about the battered prostitute and the Labrador in the suitcase. And by the time they were through all that, a red faced PC Steve Jacobs was waiting for them by the back door, clutching a small stack of A4 printouts: Graham Kennedy's rap sheet. Insch pointed his key fob at a muck encrusted Range Rover and plipped open the locks. 'Right,' he said, striding out into the rain, 'PC Jacobs, you can do the honours. DS McRae, in the back, and don't stand on the dog food.'

The inside of Insch's car smelled as if something wet and shaggy had set up residence. There was a big metal grille separating the back seat from the boot and a soggy, black nose was pressed against it as soon as Logan clambered into place, trying not to tread on the jumbo-sized bag of Senior Dog Mix in the foot well. Lucy – the inspector's ancient Springer Spaniel – was pretty, in a manipulative, big-brown eyed kind of way, but every time it rained she stank like a tramp on a bad day.

'Where to, sir?' asked PC Steve as they cruised slowly up Queen Street.

'Hmm?' The inspector was already immersed in Graham Kennedy's file. 'Oh, Kettlebray Crescent: let's get our esteemed colleague's opinion on the scene of the crime before we go tell Kennedy's granny her wee boy's dead… And the car does come with an accelerator, Constable: pedal on the floor, next to the big rectangular one. Try and use it, or we'll be here till bloody Christmas.'

Fourteen Kettlebray Crescent was a mess. Vacant windows stared out at the street, surrounded by dark streaks of soot.

The roof was gone, collapsed in on itself as the flames raged through the building. Now faint, rainy daylight filtered into the house's shabby interior. The buildings on either side hadn't fared too badly; the fire brigade had arrived quickly enough to save them. But not the six people who'd been in number fourteen. Insch grabbed an umbrella from the boot and marched off into the fire-ravaged house, leaving Logan and PC Steve to scurry along behind getting wet. A mobile incident room was abandoned outside the building: a cross between a Portacabin and a caravan, only without the windows. The standard black-and-white checked ribbon ran around the outside, with the Semper Vigilo thistle logo in the middle. Like a bow on a grubby, unwanted Christmas present.

They ducked under the blue-and-white Police tape stretched across the the burnt-out building's garden gate and walked up the path to the front door. It was hanging off its hinges, battered in by the fire brigade as soon as they realized someone was actually in there, but by then it was too late. Logan stopped at the doorframe: there were about two dozen three-inch screws poking through the wood, their shiny steel points grabbing the space where the door should have been. Inside it was like something out of Better Homes and Infernos. The walls in the hallway were stripped back to the plaster and lathe, black and covered in soot. 'Er… sir?' asked PC Steve, hanging back, peering into the gutted building from the outside. 'Are you sure this is safe?'

The upper floor was missing, leaving the building little more than a burnt-out shell, the ground floor covered in broken slates and charcoaled wooden beams. Rain fell steadily through the gaping hole where the roof used to be, drumming off the inspector's brolly. He stood in a relatively clear patch and pointed up at one of the windows on the upper floor. 'Main bedroom: that's where the petrol bombs came in.'

Logan risked a clamber over the shifting, rain-slicked slates, to peer out into the street beyond. The mud was slowly washing off the inspector's filthy car, the expectant nose of a smelly spaniel pressed against the rear window, looking up at the building where six people had been burned to death. Screaming until their lungs filled with scalding smoke and flame, falling to the floor in agony as their eyes cooked and their flesh crackled… Logan shuddered. Did it actually smell of burning people in here, or was it just his imagination? 'You know,' he said, looking away from the window and back into the hollowed-out building, 'I heard it takes twenty minutes for the human brain to die once the flow of blood's stopped… all the electrical impulses, firing away to themselves, till there's no charge left…' The ruined face, staring up at him out of the body-bag in the morgue: eyes, nose and lips gone. 'Do you think it was like that for them? Already dead, but still feeling themselves burn and cook?'

There was an uncomfortable silence. And then PC Steve said, 'Jesus, sir, morbid much?' Insch had to agree. They picked their way carefully through the debris and back outside; there was nothing else to see here anyway.

Logan stood on the top step, looking up and down the deserted street. 'What did you find when you searched the other buildings?'

'Not a bloody thing.'

Logan nodded and wandered out into the road, slowly turning through three hundred and sixty degrees, taking in the boarded-up houses on both sides of the street. If he was the sick bastard who'd screwed the door shut so that three men, two women and a nine-month-old baby girl would be roasted alive, he'd want to hang about and watch them burn. That would be where the fun was. He crossed the road, trying the door handles, looking for one that wasn't locked… Two houses up, something caught his eye, something grey and squishy, trapped in the corner of the doorframe. It was nearly invisible: a disposable tissue, soaked transparent by the rain and slowly disintegrating.

He pulled out a small, clear evidence baggie and turned it inside out, using it like a makeshift mitten to scoop up the tissue before flipping the baggie round the right way again, trapping the contents inside. A shadow fell across the doorway.