'I saw him Friday morning.’

`So you did.’

Rebus turned to Millie. She had short fair hair, dark at the roots, and dark eyebrows. Her face was long and plain, her chin highlighted by a protruding mole. Rebus reckoned she was a few years older than Murdock. 'Did he say where he was going?’

`He didn't say anything. There's not a lot of conversation in this flat at that hour.’

'What hour?’

She flicked ash into the ashtray which was balanced on her sleeping bag. It was a nervous habit, the cigarette being tapped even when there was no ash for it to surrender. 'Seven thirty, quarter to eight,' she said.

'Where does he work?’

'He doesn't,' said Murdock, resting his hand on the mantelpiece. 'He used to work in the Post Office, but they laid him off a few months back. He's on the dole now, along with half of Scotland.’

'And what do you do, Mr Murdock?’

'I'm a computer consultant.’

Sure enough, some of the living room's clutter was made up of keyboards and disk drives, some of them dismantled, piled on top of each other. There were piles of fat magazines too, and books, hefty operating manuals.

'Did either of you know Billy before he moved in?’

'I did,' said Millie. 'A friend of a friend, casual acquaintance sort of thing. I knew he was looking for a room, and there was a room going spare here, so I suggested him to Murdock.’

She changed channels on the TV. She was watching with the sound turned off, watching through a squint of cigarette smoke.

'Can we see Billy's room?’

'Why not?’ said Murdock. He'd been glancing nervously towards Millie all the time she'd been talking. He seemed relieved to be in movement. He took them back into where the narrow entrance hall became a wider rectangle, off which were three doors. One was a cupboard, one the kitchen. Back along the narrow hall they'd passed the bathroom on one side and Murdock's bedroom on the other. Which left just this last door.

It led them into a very small, very tidy bedroom. The room itself would be no more than ten feet by eight, yet it managed to contain single bed, wardrobe, a chest of drawers and a writing desk and chair. A hi-fi unit, including speakers, sat atop the chest of drawers. The bed had been made, and there was nothing left lying around.

'You haven't tidied up, have you?’

Murdock shook his head. 'Billy was always tidying. You should see the kitchen.’

'Do you have a photograph of Billy?’

Rebus asked.

'I might have some from one of our parties. You want to look at them?’

'Just the best one will do.’

'I'll fetch it then.’

'Thank you.’

When Murdock had gone, Siobhan squeezed into the room beside Rebus. Until then, she'd been forced to stay just outside the door.

'Initial thoughts?’ Rebus asked.

'Neurotically tidy,' she said, the comment of one whose own fiat- looked like a cross between a pizza franchise and a bottle bank.

But Rebus was studying the walls. There was a Hearts pennant above the bed, and a Union Jack flag on which the Red Hand of Ulster was centrally prominent, with above it the words 'No Surrender' and below it the letters FTP. Even Siobhan Clarke knew what those stood for.

'Fuck the Pope,' she murmured.

Murdock was back. He didn't attempt to squeeze into the narrow aisle between bed and wardrobe, but stood in the doorway and handed the photo to Siobhan Clarke, who handed it to Rebus. It showed a young man smiling manically for the camera. Behind him you could see a can of beer held high, as though someone were about to pour it over his head.

'It's as good a photo as we've got,' Murdock said by way of apology.

'Thank you, Mr Murdock.’

Rebus was almost sure. Almost. 'Billy had a tattoo?’

'On his arm, aye. It looked like one of those things you do yourself when you're a daft laddie.’

Rebus nodded. They'd released details of the tattoo, looking for a quick result.

'I never really looked at it close up,' Murdock went on, 'and Billy never talked about it.’

Millie had joined him in the doorway. She had discarded the sleeping bag and was wearing a modestly long t-shirt over bare legs. She put an arm around Murdock's waist. 'I remember it,' she said. 'SaS. Big S, small a.’

'Did he ever tell you what it stood for?’

She shook her head. Tears were welling in her eyes. 'It's him, isn't it? He's the one you found dead?’

Rebus tried to-be non-committal, but his face gave him away. Millie started to bawl, and Murdock hugged her to him. Siobhan Clarke had lifted some cassette tapes from the chest of drawers and was studying them. She handed them silently to Rebus. They were collections of Orange songs, songs about the struggle in Ulster. Their titles said it all: The sash and other Glories, King Billy's Marching Tunes, No Surrender. He stuck one of the tapes in his pocket.

They did some more searching of Billy Cunningham's room, but came up with little excepting a recent letter from his mother. There was no address on the letter, but it bore a Glasgow postmark, and Millie recalled Billy saying something about coming from Hillhead. Well, they'd let Glasgow deal with it. Let Glasgow break the news to some unsuspecting family.

In one of the drawers, Siobhan Clarke came up with a Fringe programme. It contained the usual meltdown of Abigail's Partys and Krapp's Last Tapes, revues called things like Teenage Alsatian Orgy, and comic turns on the run from London fatigue.

'He's ringed a show,' said Clarke.

So he had, a country and western act at the Crazy Hose Saloon. The act had appeared for three nights back at the start of the Festival.

'There's no country music in his collection,' Clarke commented.

'At least he showed taste,' said Rebus.

On the way back to the station, he pushed the Orange tape into his car's antiquated machine.

The tape played slow, which added to the grimness. Rebus had heard stuff like it before, but not for a wee while. Songs about King Billy and the Apprentice Boys, the Battle of the Boyne and the glory of 1690, songs about routing the Catholics and why the men of Ulster would struggle to the end. The singer had a pub vibrato and little else, and was backed by accordion, snare and the occasional flute. Only an Orange marching band could make the flute sound martial to the ears. Well, an Orange marching band or lain Anderson from Jethro Tull. Rebus was reminded that he hadn't listened to Tull in an age. Anything would be better than these songs of… the word 'hate' sprang to mind, but he dismissed it. There was no vitriol in the lyrics, just a stern refusal to compromise in any way, to give ground, to accept that things could change now that the 1690s had become the 1990s. It was all blinkered and backward looking. How narrow a view could you get?

'The sod is,' said Siobhan Clarke, 'you find yourself humming the tunes after.’

'Aye,' said Rebus, 'bigotry's catchy enough all right.’

And he whistled Jethro Tull all the way back to St Leonard's.

Lauderdale had arranged a press conference and wanted to know what Rebus knew.

'I'm not positive,' was the answer. 'Not a hundred per cent.’

'How close?’

'Ninety, ninety-five.’

Lauderdale considered this. 'So should I say anything?’

'That's up to you, sir. A fingerprint team's on its way to the flat. We'll know soon enough one way or the other.’

One of the problems with the victim was that the last killing shot had blown away half his face, the bullet entering through the back of the neck and tearing up through the jaw. As Dr Curt had explained, they could do an ID covering up the bottom half of the face, allowing a friend or relative to see just the top half. But would that be enough? Before today's potential break, they'd been forced to consider dental work. The victim's teeth were the usual result of a Scottish childhood, eroded by sweets and shored up by dentistry. But as the forensic pathologist had said, the mouth was badly damaged, and what dental work remained was fairly routine. There was nothing unusual there for any dentist to spot definitively as his or her work.