‘I’m going to have to leave it to you both,’ Sir Alan said. ‘I know it’s a lot to ask, and in normal circumstances I’d be with you in the trench, but I can no longer pretend that we’re in anything but the very final chapter.’

‘We can handle it,’ Ian said confidently. ‘There’s no reason to think it will be anything but straightforward.’

‘Nothing like this is ever straightforward.’

‘I understand that. But we’ll do our best.’

They left him to the gloom of his thoughts and circumstances. Kate found herself dwelling on how she would feel if she were told Stuart had terminal cancer and only weeks to live. It was hard to keep conversation with Ian going as he started to try to discuss every aspect of the operation. He had a spring in his step and she found it difficult to work out exactly why. Was it his chance to prove himself to Meg Simpson, or had he some other outcome in mind?

Suzy and Julie were waiting in the office and Kate briefed them on the decision that had been taken. Suzy appeared thrilled until Kate told her that she would have to remain in London. She argued about it until Kate put her foot down, at which she retreated into a barely disguised sulk.

Julie slipped out with her. Kate closed her door and sat with her back to it, eyes shut as she tried to still her thumping heart. The pain in her stomach and central back had grown in intensity again. She felt about a hundred years old.

Ian had made clear he was going to run the operation and had already insisted on deploying himself to Tbilisi with her, but Mikhail was her contact, so there was plenty for her to work through. She took out her phone and sent him a message, using Signal this time, as all staff were advised to do from time to time: Green light. We will arrive in Tbilisi tomorrow.

She got a reply in seconds. Good.

Kate logged on to her computer. She started researching Kazbegi, deep in the Caucasian mountains, where Mikhail had indicated his father would cross the border. She had lost herself in the task when Julie burst in. ‘Have you seen?’

‘What now?’

‘Go to the ITV website. Someone’s leaked it.’

‘Leaked what?’ Kate asked, in exasperation, but Julie didn’t dare answer and, as soon as she pulled up the site, Kate could see why. She stared at the headline, as if it belonged to a different world entirely: Russian Defector Offers MI6 Sex Video Evidence PM Is Moscow Spy.

Kate stood, physically backing away from the screen. ‘I’m counting down to your phone erupting,’ Julie said.