Stefan kept his hair cropped military-close, a neat beard with the first touches of grey that made his cheeks look more sunken than they were and brought out the blue, insomniac intensity of his eyes. His room already smelled of energy drinks, a chemical undertone to the pine-scented toiletries; curtains closed, TV on Formula One. He had three computers set up in total, a MacBook on the bed, two Panasonics on the bureau: rugged, magnesium-alloy-encased laptops of the kind used by the military. A separate 2 TB hard drive stood on the bedside table, fan whirring, connected to a Wave Box – a portable device that generously bestowed strong, password-free wi-fi to all those within five hundred metres or so. It gave us all of the internet traffic flowing through it – email, instant messages and browser sessions. There was also an array of outfits: workers’ overalls, hi-vis vests, a toolbox.

‘What’s going on?’ Stefan asked.

‘Why?’

‘I placed a wall-contact mic near the room you’re interested in. The occupant makes and takes calls on a dedicated satphone; deep encryption. Plays white noise from an audio jammer.’

Stefan showed me images he’d taken with an under-door camera. Walker’s room was neat. You saw the audio jammer on the bureau, a black box barely bigger than a cigarette packet. A suitcase had been lifted to the bed, which was made. There was a suit over the back of a chair and a bottle of whisky beside the bed.

‘Is he in there now?’

‘He left ten minutes ago. So who am I spying on? What are we doing here?’

‘A woman’s missing. She was working in Astana for Vectis, the private intelligence company. She’s vanished. We need to know what she got.’

‘Who is she?’

‘A former colleague of mine. Her name’s Joanna Lake. If you see or hear anything mentioning that name, let me know.’

‘How long’s she been missing?’