It felt good to be on the move. What he was going to learn in Exeter he didn’t know. Maybe nothing. But at least then he’d know there was nothing to learn. That would be an end in itself.

Wada was confident she hadn’t been followed from the hospital. The intruder at Caldwell’s flat had seemed more interested in Caldwell’s computer – and his photographs – than in Wada. But she was aware she had something – the facetrail stick – that the man might also have been looking for, so she couldn’t afford to be complacent. It was time to use some of the tactics Kodaka had taught her. From Paddington she went by taxi to the National Gallery, left shortly after entering and by a different door, then took the Tube to Russell Square. Access to the street was by lift and she was pretty confident none of the other occupants of the lift were anything but ordinary travellers.

At the Envoy, she asked if there’d been any parcels delivered for her. The answer was no. Not yet, anyway.

No matter. While she awaited the parcel’s arrival, she was free to investigate the contents of the facetrail stick. She hurried up to her room. Where a shock greeted her.

The small safe in the wardrobe, where she’d stowed her laptop, was not as she’d left it. The door was open. And the laptop was gone.

Nick reached Exeter around lunchtime. He stopped at the motorway service station on the outskirts for a sandwich, then drove into the centre, following his satnav to 18 Barnfield Hill.

It was a large, detached Victorian villa, bay-windowed and red-bricked. The house next door had become a doctors’ surgery, but number 18 had been converted into flats. And there was Caldwell’s name, against the bell-push for flat 6. Nick rang it. As expected, there was no response. His plan was to find someone living there who would answer, then press them for information about Caldwell and his Japanese visitor.

It never came to that. Before he could try any of the other bells, the door opened. A bald, stooping man who was probably in his seventies, dressed in a tweed jacket and corduroy trousers, took half a step out of the door, then stopped. He peered curiously at Nick. ‘Looking for someone?’

‘Martin Caldwell.’

‘Join the club. He’s a man in demand.’

‘You know him?’

‘Slightly. I’ve just been talking to his neighbours about him. He’s, er, gone missing, it appears. I’m a journalist. Well, was. I’m retired now. I first met Martin Caldwell when he was living here as a student back in the seventies. My name’s Barry Holgate.’

‘Nick Miller.’ They shook hands.

‘Miller?’ Holgate’s eyes gleamed behind his glasses. ‘You’re the fellow Caldwell was supposed to meet in London a couple of days ago.’

‘How did you know that?’