‘I really can’t help.’ There was another silence. ‘I’m sorry, Imogen, I have to go.’

‘Please, Kate. I need you.’ Her voice was imploring now. ‘I’ll make it worth your while if I get to Number Ten – any way you want me to.’

Kate was about to tell her former friend where to stick her offer when she thought better of it. What if Imogen was right and the coup she was mounting saw the prime minister rapidly shoved from office? How long would it take? A week, two at most?

And what would the prime minister’s promises in relation to Stuart count for then?

‘I knew I could rely on you,’ Imogen said – as ever running ahead of herself. ‘I’ll pop around tonight.’

Kate didn’t even have time to reply before Imogen had rung off. And she’d not put her phone back on the desk before she received a summons from the prime minister to Downing Street: Come to Number Ten immediately, the text read. JR.

Kate wasn’t expecting a welcoming committee and she didn’t get one. The prime minister’s office at Number Ten was comfortably furnished, with a cream sofa, armchairs and a coffee-table beyond the broad desk, and enough bookshelves to pass as a library, but it was small and into it were crammed the prime minister and most of his immediate team, including Shirley Grove. Kate had brought Callum with her, at his suggestion.

James Ryan slouched against the side, hands thrust into his pockets. His cheeks were puffy and red, his dark hair tangled, as if he had purposely stuck it through a hedge for this meeting. He looked visibly weighed down by the cares of office. ‘You’ve seen it all, I suppose,’ he said, gesturing vaguely at the bookshelf, as if it hid a secret TV screen running news of his latest humiliation on repeat. Perhaps it did. ‘They’re shafting me as we speak.’

‘Yes. I’m sorry, Prime Minister.’

‘What do you make of it?’ Grove asked Kate. She was the only one keeping her composure.

‘Not much.’

‘Isn’t it another turn of the Russian dial?’ Grove pressed.

‘How do you mean?’

Grove looked pained, as though she was dealing with a difficult pupil. ‘They’ve just found another way of setting up the prime minister, surely.’

Kate thought about this. It had not immediately struck her as likely, which suggested she was still struggling to believe in the prime minister’s innocence. ‘If it was Moscow, I imagine they’d have faked another video. It seems to be one of their specialities.’

‘Who’s to say that won’t emerge?’ the PM said.

‘Could it?’

‘For God’s sake, Kate.’ He walked around his desk and stared out of the window at the Downing Street garden. ‘I should have picked someone who actually believed in my innocence to run this inquiry. It was Grove’s idea to go for you.’ He spun around. ‘I’m screwed. Absolutely fucked.’ He was looking directly at Kate now, as though this were all her fault. ‘The chief whip tells me Imogen Conrad and her mutinous band are a day or two at most away from having enough letters to trigger a no-confidence vote. So that probably means I could be staring down the barrel of political annihilation in a week’s time. You think you’ll be able to prove I’m being set up by then?’