‘And he took you where?’

‘The station. I got the train home. Cost me an arm and a leg, it did. I should have got the insurance to stump up for that.’

‘Was that Hartlepool station?’

Naylor hears a few seconds of empty static.

‘I’m sorry,’ Birch says at last, ‘you’re breaking up again.’

‘Hartlepool. Was it Hartlepool?’

‘Yes, Hartlepool. Took me into Euston and I found my own way easy enough from there. Look, I’m sorry but I’m just going into a meeting. Is there anything else I can help you with?’

‘No, thanks, you’ve been very helpful,’ says Naylor. ‘Thanks for your time.’

When the call’s ended, Birch turns into a residential side street and finds a space to park. Picking up the phone he’s just been speaking on, he copies a couple of entries from the contacts book into the second pay-as-you-go, before removing the back of the first phone and taking out the SIM.

The battery and the casing are easily separated. He tosses both into the passenger footwell, puts the car into gear and drives away.

The café’s all on-trend retro, duck-egg-blue paint and artisan breads, a menu board of coffee beans from South America and the Caribbean. It’s the kind of place Hagen hates, and she’s glad he’s not with her; he would have gone in the chip shop two doors down. But Naylor’s pleased to choose from sandwich options which include hummus and green olive ciabatta. She plumps for that with tapenade and turkey, and asks them to add some chipotle mayo to make it interesting. She gets a bottle of water and a Costa Rican flat white to drink, but resists the white chocolate brownies for the sake of her waistline and her purse.

She finds an empty corner table with a good view of the street, where she can watch the comings and goings of kids in school uniform buying lunch at the chippy and the newsagent’s. Some of them are young, about the age Evan was when he was taken, and too many of them seem obsessed with their phones. Naylor’s all too aware of the dangers that lurk behind those screens and buttons: predators, groomers, the creeping and irrevocable loss of innocence. No wonder clued-up Silicon Valley bosses are sending their children to schools where technology is banned. When parents first gave kids phones, their main reason was for safety, but Evan’s phone did nothing to save him. It disappeared and went silent only minutes after he went missing, switched off and no doubt chucked in some river or dropped down a drain.