Stein had also left Israel a full twenty-four hours before Rachel had gone missing. It was possible that his departure had triggered her disappearance; and possible, given how terrified Moshe said she’d been, that she’d known something was going to happen to her. Perhaps she’d sent Stein and his message back home while she still could – as a failsafe, an insurance policy in Moshe’s words. But against what?

‘Sorry I’m late.’

Baaz sat down in the chair next to me and set his laptop on the table. It was as if he was connected to its shiny silver case by an umbilical cord; a digital witch’s-familiar for the twenty-first century. He’d switched his simple black turban for a crimson one and marshalled what passed for his beard into a neat series of wisps. I ran the back of my hand over my chin and made a mental note to ask housekeeping for a razor.

‘I’ve been thinking about the dates,’ he said, ‘and about that Russian joker, too, who you said turned up in Paris, in the catacombs.’ Baaz sipped from my untouched glass of orange juice. ‘The boss man.’

‘Who, Avilov?’

‘Yeah. By my calculation, he arrived here in Israel a couple of days before you started the stakeout, at the cottage.’

‘Reconnaissance. We do reconnaissance, not stakeouts. But yeah, that’s correct – assuming Talia isn’t spinning us a line.’

Which was always possible, of course. Ezra had said that she was on the side of the angels – though from where I was standing that was no longer necessarily a good thing. The fact she had that book of matches meant she’d definitely known more than she was letting on. It seemed unlikely that she’d given them to me in Rachel’s office by accident.

‘OK, whatever. But then he pops up again on that ship in the English Channel, where he’s trying to keep you alive – sort of. That’s when you first meet him, right?’ Baaz was speaking fast now. I got the feeling sometimes that if he could entirely dispense with words and just use numbers, he would.

I nodded. ‘So?’

‘So that means he’s behind the curve. Don’t you see? He’s trying to solve a problem, too. He’s got his own equation and the reason he, or whatever boss-Russian he works for, wants you alive is because they think you can solve it for them – just like the Israelis, probably.’

‘OK. But why not just take the banknote? He had me strung up by my ankles – and what, his goons didn’t even think to search my pockets? Any amateur would have done that. It doesn’t make sense.’

‘Variables. Your equation has variables. His equation has variables. Unknown variables. Same–same. You’re both in the dark. And then, boom!’

‘There have been a lot of booms so far, Baaz. Which one is going off now?’