‘As part of a healthy lifestyle, Sergeant?’ asked Proust. Simon stopped himself from smiling just in time. He’d never laughed at one of the Snowman’s witticisms and wanted to keep it that way.

‘I’m waiting till the food arrives,’ said Gibbs. ‘I’m fucking starving.’

‘Waiting to do what, detective? Burst into song?’

‘Talk,’ Gibbs clarified.

Sellers was pushing his way through the crowd towards their table. He had a pint in one hand and was unbuttoning his coat with the other. ‘Congratulate me,’ he said.

‘Another blind woman pregnant?’ Gibbs muttered.

‘Shut it, gobbo. I hope you ordered for me.’

‘Yeah. Weight Watchers bar, wasn’t it?’

Sellers made a face. ‘I think I’ve found Lane the Ishaya. If I’m right, her full name’s Marjolein Baillie. Lives in Rawndesley. She’s an Ishaya of something called the Bright Path, whatever that means. Known to family and friends as Lane. I spoke to her husband – she’s away till next Tuesday on a meditation retreat, but we can speak to her the next day, the Wednesday.’

‘Another reason to think Billy’s local,’ said Simon. ‘His therapist, mentor, whatever is Culver Valley-based, as were two of his victims, as is Kim Tribbeck who he might have lined up as a future victim.’

‘I was just saying I think books are important, whatever else is,’ Sam filled Sellers in. ‘Billy gives his victims books before killing them, he sends Sondra Halliday a book, he admires someone called Lane who teaches through story. But why those lines of poetry, and why Beloved by Toni Morrison? We ought to be able to get something from that. We’ve got not only his choice of victims to go on now, but also his choice of literature.’

‘You’re assuming Billy wrote the letter to Sondra Halliday,’ said Simon.

‘He did.’ Sellers looked around for somewhere to dump his coat. Not finding anywhere convenient, he folded it up, put it on his chair and sat on it. ‘Report just came in from the prof. In court, he’d have to say there was an 80 per cent chance the writing was Billy’s, same as in the little white books—’

‘80 per cent? Is that all?’ said Proust. ‘Can’t he do better? As he’s not a real professor, I’m not sure his opinion has any worth.’

‘Malcolm Coulthard’s a world expert in forensic linguistics and author identification,’ said Simon. ‘“Emeritus” doesn’t mean “not real”. He was the Foundation President of the International Association of Forensic Linguists, an expert witness in more than two hundred criminal and civil cases. Experts don’t come much better. Plus, if you’re going to hold a grudge against him for being technically retired, didn’t he say he’d consult with the professor who now runs his old department?’