'How's DI Steel taking it?' asked Logan.

'Hmm? Oh…' Insch's smile faded. 'Well she's happy about the nose-punching but well pissed off they let that slimy little pervert go free.' He shook his head. 'She spent ages getting the victims to testify. Poor buggers had to stand there and tell everyone what that pervert did to them. Hissing Sid humiliates them. Cleaver goes free, and all that pain was for nothing.'

Silence settled over the table, everyone concentrating on their soup.

'You want to go see him?' asked Insch when the last of Logan's soup was gone.

'What, Cleaver?'

'No, the hero of the hour!' He raised his hands in the classic fisticuffs pose. 'He who floats like a butterfly and stings like a fist to the nose.'

Logan smiled. 'Why not?'

There was a small crowd outside the holding cells. All happy and chattering. With a growl, DI Insch sent them packing. Didn't they know this was highly unprofessional? Did they want people to think it was OK to go committing assault? Shamefaced, the uniformed onlookers dispersed, leaving just Logan, Insch and the custody sergeant outside the blue-painted door. The sergeant was scribbling a name on the board next to the cell and Logan frowned. It looked familiar, but he couldn't work out why.

'Mind if we pay your boy a visit?' asked Insch when the scribbling was done.

'What? No, sir, you go ahead. Are you in charge of the investigation?'

Insch beamed again. 'I bloody well hope so!'

The room was small without being cosy: brown lino floor, cream walls and a hard wooden bench-seat running along the wall. The only natural light came from two small frosted panes of heavy-duty glass set into the top of the outside wall. The whole place smelled of armpits.

The cell's occupant was curled up on the wooden bench, lying on his side in the foetal position. Moaning quietly.

'Thank you, Sergeant,' said Insch. 'We can take it from here.'

'OK.' The custody sergeant backed out of the cell and winked at Logan. 'Let me know if Mohammed Ali here gives you any trouble.'

The cell door shut with a dull clang and Insch settled down on the bench next to the curled up figure. 'Mr Strichen? Or can I call you Martin?'

The figure shifted slightly.

'Martin? Do you know why you're here?' Insch's voice was soft and friendly, completely unlike any tone Logan had ever heard him use on a suspect.

Slowly, Martin Strichen levered himself up until his legs were hanging over the edge of the bench, his socks making damp footprints on the lino. They'd confiscated his shoelaces and his belt and anything else dangerous. He was huge – not fat – but large everywhere, arms, legs, hands, jaw…Logan stopped when he got to the pockmarked face. Now he knew where he recognized the name from: Martin Strichen was WPC Watson's changing-room wanker, the one he'd given a lift back to Craiginches Prison. The one who'd been giving evidence in the Gerald Cleaver case.

No wonder he'd smacked Slippery Sandy on the nose.

'They let him go.' His voice was little more than a whisper.

'I know they did, Martin. I know. They shouldn't have, but they did.'

'They let him go because of him.'

Insch nodded. 'And that's why you hit Mr Moir-Farquharson?'

A muffled mumble.

'Martin, I'm going to write up a little statement and then I'm going to ask you to sign it, OK?'

'They let him go.'

Gently, Insch took Martin Strichen through the events of the afternoon, taking special delight in the moment of impact, getting Logan to write it all down in tortured police-speak. It was an admission of guilt, but Insch had taken great pains to make it sound as if it was all Sandy the Snake's fault. Which it was anyway. Martin signed it and Insch released him from custody.

'Do you have anywhere to go?' asked Logan as they walked him through reception to the door.

'Staying with my mother. The court said I have to, while I do my community service.' His shoulders sagged even further.

Insch patted him on the back. 'It's still raining; I can get a patrol car to give you a lift if you like?'

Martin Strichen shuddered. 'Said she'd kill me if she saw another police car outside the house.'

'OK. If you're sure.' Insch extended his hand and Strichen shook it, his huge paw engulfing the inspector's. 'And, Martin,' he looked into the lad's troubled hazel eyes, 'thank you.'

Logan and Insch stood at the window, watching Martin Strichen disappear into the rainy afternoon. Only four o'clock and it was already dark outside.

'When he was on the stand,' said Logan, 'he swore he'd kill Moir-Farquharson.'

'Really?' Insch sounded thoughtful.

'You think he'll try something?'

A smile broke across the inspector's face. 'Let's hope so.' There were no smiles in interview room number three. It was packed to the gunwales with DI Insch, DS McRae, a damp WPC, and Duncan Nicholson. The tapes in the recording unit whirred away to themselves, the red light on the video camera winking away in the corner of the room.

Insch leaned forward and smiled the kind of smile crocodiles reserve for sick wildebeest. 'Sure you don't just want to come clean, Mr Nicholson?' he asked. 'Save us all a lot of trouble. You just cough to it all and tell us what you've done with Peter Lumley's body.'

But Nicholson just ran a hand across his shaved head, making scratching noises as he wiped the sweat away. He looked awful – shaking, sweating, arms wrapped around himself, eyes darting from Logan to Insch to the door.

Insch popped open a clear plastic wallet and pulled out a photo of a little boy on a tricycle. The child was in what looked like a back garden, the strut of a whirly washing line visible between an out-of-focus towel and a pair of jeans. Insch held up the photo with the image facing away from him so he could read the name in biro on the back. 'So tell me, Mr Nicholson, who's Luke Geddes?'

Nicholson licked his lips and darted a nervous glance at the door, the wet WPC, everywhere but the child on the bike.

'Is he one of your little victims, Nicholson? Next on your list for picking up, killing and screwing? No? What about this one-' Insch dug another photo out of the wallet, a little blond boy in his school uniform, walking down a street alone. 'Stir any memories? Stir anything else? Get you hard, does it?' He pulled out another photo. 'What about this one?' Little boy sitting on the back seat of a car, looking scared. 'This your car? Looks like a Volvo to me.'

'I didn't do anything!'

'Bollocks you didn't. You're a lying wee scumbag and I am going to send your arse to jail till you die.'

Nicholson swallowed hard.

'We have some other photographs,' said Logan. 'Would you like to see them, Mr Nicholson?' He turned over a manila folder and took out the pictures of David Reid's post mortem.

'Oh God…' Nicholson went grey.

'You remember little David Reid, don't you, Mr Nicholson? The three-year-old you kidnapped, strangled and raped?'

'No!'

'Surely you remember him? You went back for bits of him didn't you? With a pair of secateurs?'

'No! God, no! I didn't do it! I only found him! I didn't touch him!' He grabbed at the table as if he were about to fall off the floor and slam into the ceiling. 'I didn't do anything!'

'I don't believe you, Duncan.' Insch gave his crocodile smile again. 'You are a filthy wee shite and I am going to put you away. And when you're up in Peterhead Prison you're going to find out what happens to people like you. People who fiddle with kids.'

'I didn't do anything!' Tears streamed down Nicholson's face. 'I swear I didn't do anything!' A half hour later DI Insch suspended the interview, using the excuse of a 'comfort break'. They left Duncan Nicholson in the interview room with the soggy WPC and strolled back to the main incident room. Nicholson was a wreck, sobbing, wailing, trembling. Insch had put the fear of God into the man and now wanted him to stew in his own juices.