Simon had known something like that was coming. The Snowman had taken to calling the Dorset detective ‘the Wing beneath your wind’. ‘I’ve heard nothing,’ he said. ‘Gibbs is right: everyone’s waiting on us.’

‘I just can’t see a way forward.’ Sam sounded despondent.

‘Don’t say that.’ Simon looked up from his pint of Diet Coke. ‘We’re making solid progress. We’ll get the DNA results from our recent batch of samples soon – we might strike lucky.’

‘How soon?’ asked Gibbs.

‘They can’t tell me. Not today, that’s for sure.’

‘Knowing Backlog Towers, all our potential Billies will be dead before we get those results,’ said Proust. ‘I’m surprised they’re still answering their phones.’

‘I told them it was top priority,’ said Simon. ‘I think they’ll do their best to get to it. They said they might send the samples on to another lab if they couldn’t get to them in the next day or so.’

‘Pathetic,’ the Snowman snapped.

‘Anyway, Liam Sturridge is the latest piece of the jigsaw to slot into place,’ said Simon.

Sellers and Sam exchanged a baffled look.

‘I thought Sturridge told you nothing,’ said Gibbs.

Simon nodded. ‘That’s right. He must remember the town where he and Kim Tribbeck stayed in a hotel last year. He pretended not to – why? Both of them say it was the only time they ever spent a night anywhere but Kim’s cellar. I asked him if he often stays in hotels. Never, he said. So it’s not plausible that he doesn’t remember where it was. He was lying, and he knew I knew it.’

‘And you call that a piece of the jigsaw slotting into place?’ Sellers asked.

‘It’s not an answer – the opposite – but it’s part of the whole picture. The things that don’t make sense are as vital as the things that do. Liam Sturridge lied. Why? Could mean something, could mean nothing. He wouldn’t answer at all until I’d answered his question: didn’t Kim remember where it was? When I told him no, she didn’t, he said, “Neither do I”. I sensed he didn’t want to give us any information we hadn’t already had from her – either because he cares about her and thinks he needs to protect her, or …’ Simon broke off and shrugged. ‘For what it’s worth, I don’t think he gives a crap about Kim, or about helping us stop a killer or anything. I’ve never spoken to a more disengaged-sounding person.’

‘Simon’s right,’ Sellers confirmed. ‘I interviewed Sturridge face to face. The radiator on the wall next to him had more personality.’