They knew just the place, it seemed. We took the Renault to an address in the business district, a rectangular block of mirrored glass. Walker swiped us in. The floors housed KPMG, PwC, software and construction companies. Ours apparently belonged to a law firm called White and Chase, with a desk and logo, a smiling receptionist, and nothing else whatsoever as far as I could see. We walked past empty conference rooms to a heavy door with keypad entry, into a windowless office with three monitors and a Faraday cage to block the transmission of radio waves. It was a secure compartmentalised facility: a SCIF, in intelligence community parlance. I was searched before we went in.

Inside I checked the technology – Dell screens, external hard drives, ethernet box on the wall. I produced my flash drive and they unlocked a safe in the corner, withdrew a Lenovo laptop with a USB port. It booted up to an empty desktop and factory settings. Walker inserted the drive. The guard stayed by the door at first. When Walker had watched the clip once he nodded consent and beckoned him over.

They watched it together.

‘How did you get it?’ Walker asked.

‘She sent it to me.’

‘No audio?’

‘Unfortunately not.’

‘Know the other man?’

‘No. But I think this may be a room in the Triumph of Astana.’

‘What do you mean “may be”?’

‘It’s faked.’

‘Are you sure?’

‘Given that I’ve never been there, it seems likely. Did Joanna assign cryptonyms?’

‘No.’

‘The video’s titled Catalyst.’

Walker shook his head, blankly. ‘You may not be the best person to be visible here,’ he said.

‘Well, here I am. So far I’ve only had one gun pulled on me today.’

‘You say someone approached Testimony, that Joanna might have been in receipt of information from that source?’

‘Elena Yussopova suggested as much. I couldn’t get any more out of her.’

‘Does she trust you?’

‘I wouldn’t go that far. She’s not actively campaigning against me yet.’

Walker reached into a desk drawer and produced a single cigarette. He used a silver lighter with a small blue flame, pressed a button and a fan under the desk sucked the smoke away in a descending stream. Then he continued to watch me, assessing.

‘What do you want?’

‘Give me access to what you’ve got so far. I’ll find her for you.’

He sighed. ‘Do you speak Kazakh?’

‘Of course. Who’d try and operate in a country without the language?’

‘What’s your current status with regard to Six?’

‘I’m on holiday.’

‘We would have to think how to do this.’

‘Sure. It’s a sensitive situation.’

Walker sat silently for some time, eyes open and bloodshot. I tried to imagine what he was thinking: maybe it was about the beach he’d recently been on.

‘I’d like to send the footage for more thorough analysis,’ he said, finally.