‘Then I don’t get it. What are you doing there?’

‘I asked her to meet me. I wanted to have another go at—’ Sellers broke off. ‘Look, that’s not important. Here’s what is: Angela McCabe bought Josh various presents he didn’t want, but that he kept anyway. Lisa’s about to take them home with her, knowing they mattered to Josh on a sentimental level. I happened to see them in a bag, waiting in the bathroom to go to her house. One of them struck me as being possibly significant.’

‘In the bathroom?’ said Simon. ‘Do you think she was trying to hide them from you?’

Sellers frowned. ‘No. At least … that hadn’t occurred to me. I mean, I was bound to go into the bathroom at some point, so she didn’t hide them very well.’

‘Go on. What were they?’

‘A butter dish, a Kindle, a grotesque tie with Star Wars characters on it and a recipe book – written by guess which celebrity chef?’

When no answer came, Sellers examined his phone to check he hadn’t lost reception. ‘Simon? Are you there?’

Still silence.

‘Simon!’

‘Yeah, I’m here.’

‘Oliver Halliday – that’s whose recipe book Angela McCabe bought Josh Norbury. Other half of Sondra.’

‘Obviously. Who else was it going to be but the Hate Preacher’s husband, if you’re this excited about it?’

‘You don’t sound excited.’

‘I’m not.’

Sellers felt winded for the second time in one day. He’d made a fool of himself yet again.

‘The reason I’m not excited is that we’re there now. We have our answer, thanks to you. We’ve got Billy.’

‘What?’

‘You ought to understand the thrill-of-the-chase factor better than anyone. It’s being close to getting there that’s exciting. Once you know all the answers …’ Simon sighed. ‘Obviously we still need to get the confession, but that’s a different kind of challenge.’

‘All the answers? I don’t know any of the answers.’

‘Really? Think about what you’ve just told me.’

‘But … So you reckon it’s definitely significant? I mean, people all over the country have got Oliver Halliday’s book. It was everywhere when it first came out. There’s probably a copy in my kitchen. Stacey buys more food books than she makes meals these days.’ Sellers’ new healthy eating regime had apparently put his wife off cooking.

‘So? Two, two hundred or twenty thousand people might own copies of Oliver Halliday’s book. It’s irrelevant.’

‘Okay.’ Sellers ran his free hand through his hair. ‘Okay, so … who’s Billy, then?’ Everything had been pointing towards Isobel Sturridge, but Sellers couldn’t see how Isobel could have anything to do with this recipe book.

So who could Billy possibly be?

‘Lisa Norbury?’ said Sellers tentatively. ‘The only other two people associated with this copy of Oliver Halliday’s book are dead: Angela McCabe and Josh, but … I know Lisa’s not a killer.’

‘So do I.’

‘Then who?’ said Sellers. ‘Sondra Halliday? Oliver Halliday himself?’

The silence in his ear sounded more dead than alive.