That evening he was meeting Mike Bennett, an old university friend, now a barrister, for one of their monthly get-togethers over a drink. The venue was, as usual, a smart pub overlooking Blackheath Common. Nick tried to put Caldwell out of his mind and concentrate on Mike’s account of an entertainingly convoluted libel case he’d handled recently, but his thoughts kept drifting back to Caldwell. This didn’t escape Mike’s attention. Eventually, Nick ended up telling him all about the mystery that had recently seeped into his life.

‘You’re not going to be able to let go of this, are you?’ said Mike when he’d finished.

‘Can’t see I’ve got much choice in the matter.’

‘You could always do what this Takenaga woman seems to have done.’

‘What do you mean?’

‘Run the guy to earth. After all, you do know where he lives, don’t you?’

‘Yeah, but …’ Nick’s words drizzled into silence.

‘Exactly.’ Mike raised a satirical eyebrow at him. ‘But what?’

Wada felt exhausted by her verbal fencing match with Holgate. There was more she’d have liked to ask him, but that would only have made it obvious to him that she was holding something back. Her entrenched suspicion of journalists made it unlikely she’d ever confide in him. But … ‘You never know’ – one of Kodaka’s favourite sayings – came into her head and made her smile at the memory of how he would say it. She could still hardly believe she was never going to hear his voice again. But so it was. She acknowledged his posthumous advice with a little nod and slipped Holgate’s card into her bag.

The facetrail computer stick was safely stored in there as well. She was eager to know what was on it, but couldn’t find out without returning to London, or using somebody else’s computer, which she couldn’t imagine being able to arrange safely.

For the moment, all she could do was use her phone to look up facetrail on the internet. She got a hit straight away. According to its website, Facetrail offered a search service for missing persons. It used an existing photograph or likeness of the missing person to trawl through millions of online images, seeking a match. It claimed its finely tuned algorithms put it way ahead of any similar service. It claimed, indeed, to be foolproof. If they’re out there somewhere and there’s an image of them, we will find them for you.

Had Caldwell been trying to find someone? It certainly looked like it. But who? Maybe the answer was on the stick. And maybe that answer was why he’d gone to Iceland.