Kate sat back. ‘I’m afraid that’s classified.’

‘You were conducting interviews related to the inquiry you believe you’ve been empowered to pursue?’

‘I have the prime minister’s instructions in writing.’ As she said it, Kate recalled that these had been requested but not yet delivered. She quietly cursed her own sloppiness.

‘We can keep going around the houses here, Mrs Henderson,’ Williams said. ‘Or we can go the police route.’

‘That’s not going to change the fact that what I was doing in Prague was classified. And if you’re in any doubt about that, I suggest you call the prime minister yourself.’

Williams rewarded her with another thin smile. ‘You met a senior member of the Czech Foreign Intelligence Service.’ She took a photograph from the pile of papers in front of her. ‘And then an agent of the Russian Foreign Intelligence Service.’

The picture showed Kate sitting with the SVR operative who had introduced herself as ‘Nina’. And now she genuinely cursed her own carelessness. How could she not have spotted Suzy Spencer’s watchers on her tail? She glanced at her former deputy, who had a glint of triumph in her eye. ‘We have identified her as Tanya Mikhailova. She is the deputy director of the London Desk in Moscow Centre.’

‘I’m afraid my work in Prague was classified.’

‘Not to us.’

‘Above your pay grade, Ms Williams.’ But even as she said it, Kate was aware that she was not going to be able to patronize herself out of the corner she’d marched herself into.

Williams opened her arms. ‘Must we go around the houses each time, Mrs Henderson, or could we just get on with this?’

‘Let’s get on with it,’ Kate agreed.

‘We can’t see what reason you would have to meet your handler at short notice and at considerable risk in Prague unless it was to update her on how the search for Agent Dante was proceeding.’

‘You mean the search for myself?’

‘Precisely. But you would need a scapegoat, of course.’

‘Who do you think I have in mind?’

‘That is not a subject of this discussion.’

Kate shook her head. ‘Look, I understand you’re trying to do your job here, Ms Williams. We both are. But I’m sure you will appreciate that I do not feel at liberty to discuss what transpired in Prague, or in any other part of my inquiry, without the express permission of the man who authorized the investigation, the prime minister himself.’

Kate saw the flicker of doubt in the blonde girl’s eyes. She did not have her colleague’s poker face.

Whoever had given them the authority to sit there, it was not the prime minister. And that meant it was probably not Shirley Grove either, which only deepened the mystery. How had they discovered the existence of Agent Dante?

Unless this was the work of Dante, desperately trying to halt the investigation that would inevitably end with his exposure and ruin.

‘I believe,’ Williams said, ‘that it is your current working theory that Dante has helped mastermind the greatest misinformation play we have ever witnessed, all of which began with you being duped into bugging a conversation on board Igor Borodin’s super-yacht.’