Kate took out her phone, checked the Wi-Fi hadn’t hooked up to the hotel’s system, then sent him a Signal message. We’re here.

She got a reply straight away. Good. Will let you know where to meet tomorrow 10 a.m. Be ready.

Kate answered: Would rather we set venue.

But Mikhail was obdurate: No, this is our backyard. Do as we ask.

‘I bet you a hundred quid he shags her on this trip,’ Julie said.

‘He’s just trying to make you jealous.’

‘That may have been his original intention, but he’s loving the attention. He won’t be able to resist. You know what it’s like, the excitement of your first big foreign gig. She’ll be all over him like a rash.’

‘He’s not that stupid.’

‘He absolutely is and you of all people know it.’

Kate thought about having a word with Suzy and warning her off. But she actually felt a little sorry for both of them. Their loneliness was so transparent. ‘Would you be upset?’ she asked Julie.

‘Not in the slightest.’

‘Are you sure about that?’

‘One hundred per cent certain. Every time I look at him, I feel a bit sick at what happened between us. I can’t imagine what I was thinking.’ She could see the scepticism in her friend’s face. ‘Genuinely, honestly.’

Kate was struck by her colleague’s ability to cleave off a set of unwanted emotions. No wonder Ian was so shaken by it.

Ian and Suzy arrived together. Perhaps he’d continued his tour of Georgian history all the way to her room. Suzy had booked a restaurant a short walk from the hotel, and since it was still a balmy evening, they took a table just beyond the rose-covered pergola on the terrace. Ian demanded a menu in Georgian, rather than English, and ordered for all of them. The food – tender green beans with soft walnut paste, beetroot quenelle and lightly fried corn bread, a Georgian speciality – was better than the conversation. Ian marched on with his history lesson, gesturing wildly at the twinkling lights of the city beneath them. He’d arrived in 1990, the Service’s first man in – ‘an incredible opportunity for an ambitious young officer’ – and he gave Suzy a blow-by-blow account of that era, from Gamsakhurdia’s departure for Armenia and Chechnya to the long rule of Eduard Shevardnadze, Gorbachev’s foreign minister, of whom Ian was an unreconstructed fan.

But just when Kate’s thoughts had wandered inexorably back to Sergei’s stricken face, Ian turned to her. ‘Have you been in touch with our man?’ He glanced around them to check they were not overheard.

‘Yes. He’s here.’

‘What about his father?’

‘I assume so, but I didn’t ask.’

‘Where are we going to meet?’

‘He said he would set the venue, but to be ready to move at ten a.m.’