Kate shook her head. ‘I don’t know if Stuart was Viper or not, or if he was, whether someone bigger and more import ant was left behind. He swore to me on our drive to St Petersburg that he never passed on any important operational details about my work.’

‘And you believed him?’

Kate went to the window, pulled back the curtains and gazed up at the snowy peak of Mount Kazbegi. ‘I don’t know. I wanted to.’

‘But he’s lied to you and cheated on you before.’

‘True, but he’s desperate for reconciliation.’

‘He says he is.’

‘He’s not a good actor.’ Kate turned to face her friend again. ‘Perhaps they’ve just found a way to track my movements that I have yet to work out. I don’t know. We may never know. If you’re asking me, I suspect Igor or some of his people were alerted to my presence in Russia, perhaps by someone at the border, and resolved to eliminate Sergei lest he undermine their story or spoil their plan to defect in any way. Nothing else makes sense to me.

‘So, I return always to the same point. I think this offer to come over to us is real. The video looked credible. The politics of what happens after this may prove very complicated and, the way I feel, I might not want to be around to witness it. But that’s a battle for another day.’

‘What do you mean, you might not be around to witness it?’

‘I have to sleep.’

‘If you’re resigning, so am I.’

Kate was already reaching for the zopiclone in her bag. Julie took the hint and withdrew.

Perhaps it was the purity of the mountain air, but Kate slept until about eight the following morning. There was no sign of Igor and Mikhail, so she helped herself to coffee and a croissant from the lavish breakfast laid out on the dining table and ate it on the terrace. After that, she left by a side gate and walked down to the Gergeti Trinity Church, which was thronged with tourists even at that time of the morning, the monks fussing around the under-dressed women, demanding they cover their legs and heads.

By the time she returned, Igor and Mikhail stood by the SUV, with Mikhail’s wife and young son. Another was just pulling up behind it. ‘We need to go,’ Mikhail said.

‘What’s the rush?’

But he waved away the need for an answer. Julie came out, still eating her croissant, and they got into the back of the second SUV. ‘What’s going on?’ Julie asked Kate, as the doors were closed on them. Kate shrugged.