‘I was remembering a bit of graffiti from primary school. It was in the boys’ toilets.’ He wrote it down on the paper serviette.

LOLO
AQIC
I82Q
B4IP

Siobhan read it aloud and smiled. ‘Be-fore I pee,’ she repeated. ‘You think maybe that’s what B4 means?’

He shrugged. ‘Could be part of an address.’

‘Or a coordinate … ?’

He looked at her. ‘From a map?’

‘But which one?’

‘Maybe that’s what the rest of the clue tells us. How’s your Scots Law?’

‘The exams were a while back.’

‘Ditto. Is there some Latin word for “dear”, maybe something to do with the law?’

‘There’s always the library,’ she suggested. ‘With a big bookshop just past it.’

He checked his watch. ‘I’ll go put more money in the meter,’ he said.

Rebus was at his desk, five sheets of paper spread out in front of him. He’d shifted everything else on to the floor: files, memos, the lot. The office was quiet: most of the shift had headed to Gayfield Square for a briefing. They wouldn’t thank him for the obstacle course he’d constructed in their absence. His computer monitor and keyboard now sat in the centre aisle between the rows of desks, just next to his multi-tiered in-tray.

And on his desk, five lives. Five victims, possibly. Caroline Farmer the youngest. Just sixteen when she’d disappeared. He’d finally got through to her mother this morning. Not an easy call to make.

‘Oh my God, don’t tell me there’s news?’ That sudden blooming of hope, wizened by his response. But he’d found out what he had to. Caroline had never come back. There had been unconfirmed sightings in the early days, when her photo was in all the papers. But nothing since.

‘We moved last year,’ her mother said. ‘It meant emptying her bedroom …’

But for the quarter-century before that, Rebus surmised, Caroline’s room had been waiting for her: same posters on the walls, same early-seventies teenage girl’s clothes neatly folded in the chest of drawers.

‘Back at the time, they seemed to think we’d done something to her,’ the mother continued. ‘I mean, her own family.’

Rebus didn’t like to say: all too often it’s a father or uncle or cousin.

‘Then they started picking on Ronnie.’

‘Caroline’s boyfriend?’ Rebus guessed.

‘Yes. Just a laddie.’

‘They’d split up, hadn’t they?’

‘You know what teenagers are like.’ It was as though she were talking about events from a week or two back. Rebus didn’t doubt that the memories stayed fresh, always ready to torment her waking hours, maybe even the sleeping ones too.

‘But he was ruled out?’

‘They gave up on him, yes. But he wasn’t the same after that, family moved from the area. He wrote to me for a few years …’

‘Mrs Farmer—’

‘It’s Ms Colquhoun now. Joe left me.’

‘I’m sorry.’

‘I wasn’t.’

‘Did it have … ?’ He stopped. ‘Sorry, none of my business.’