Igor’s gaze never left her face. ‘Your prime minister works for us,’ he said. ‘I recruited him myself in Kosovo. If I don’t get on that plane, you will never prove it and the truth will die with me here in the Caucasus.’

‘I understand that.’

‘You have a duty to your country to take us with you.’

Kate shook her head. ‘Let me talk to Ian for—’

‘No!’ Igor gripped her arm furiously again. ‘That joker. You want to know how we have been aware of your every move? The operation in Andros? Your deputy Rav on a plane to Geneva?’ He gestured contemptuously at Ian, who was dancing from one foot to the other in a bid to contain himself. ‘Because that useful idiot is so desperate to be C, he tells your prime minister everything and always has, even when he was foreign secretary. And what Ian told him, James Ryan passed on to us.’ He shook his head. ‘There was no other source, as you have been wondering, but just your superior’s relentless ambition and loose tongue.’

Kate felt dazed. ‘But I never told Ian I was coming to St Petersburg and—’

‘Come on, Kate. Wake up! The GRU has known for a long time your Russian lover Sergei was leaking material. It was all we could do to get you off that train in one piece. I saved your life. Now you must do the same for me and my family.’

Kate looked back at Ian. Of course. It explained so much. How could she not have imagined he would do anything – anything at all – to make it into Sir Alan’s chair? ‘I can’t.’

Igor leant closer. His cheeks were bright red now. ‘This is your last chance, or the truth dies with me.’

‘I’m sorry. I can’t.’

‘You’re a fool!’ Igor spun away from her.

‘Mr Borodin,’ Ian pleaded, as he stormed off. ‘I will call the prime minister . . .’

But Igor paid him no more attention. He stalked towards the plane and, moments later, he, Mikhail and the rest of their group hurried back towards the terminal. ‘For God’s sake, Kate,’ Ian said. ‘I need to speak to the PM. This is a catastrophe.’

Kate called Danny. ‘I need you,’ she said. ‘We’re in the private terminal.’

Kate climbed back onboard. She ignored Ian, who was in a state of advanced panic, swinging wildly between fury at her, feigned concern for her children and fear as to the impact of this debacle on his career.

Danny arrived and, from then on, Kate entered a narrow tunnel, the intense terror that gripped her giving everything she said and did vivid focus. They started by pulling up the CCTV all around her house in Battersea as the plane took off.