Cavalier found the train’s doctor. Screens were erected in the middle of the carriage and Natalia was examined. The French doctor told Haut and Cavalier she needed urgent surgery.

‘She’s booked into the Val-de-Grâce,’ Cavalier said.

‘How did you arrange that?’ the doctor asked. ‘It’s an exclusive military hospital used by the armed forces and the French elite.’

‘I was in there once for a short stay.’

‘For treatment?’

‘Severe lead poisoning.’

Natalia slept for the first hour of the 150-minute, 500-kilometre trip. Once the train was hurtling along the track to Paris through rural France, she awoke and insisted she talk to Haut about ‘something serious’.

‘My name is not Natalia, but Valeria,’ she said, tears welling. ‘I came into England on a false passport.’ She paused to smile faintly and added, ‘I prefer my new name. Please continue to call me Natalia.’ Haut let her continue but was concerned as every sentence caused her physical pain, and perhaps mental too. She lowered her voice.

‘Please believe me,’ she said, her hand squeezing his arm. ‘I am in love with you. This is true. But I had to have a false ID because … because …’

‘Take it easy, darling,’ Haut said, holding her. ‘Rest now. You can tell me in Paris.’

‘No,’ she said, ‘you must know now. My father …’ Natalia pulled out her phone, excused herself and rang her father in Moscow. She had a tearful chat on the phone for ten minutes. After it, she said, ‘My parents will fly to Paris tonight.’

‘From Moscow? Can they do that at such short notice?’

‘This is what I wanted to tell you. My father, you see, is very high up in the security police.’

‘The KGB?’

Natalia shook her head.

‘No, SVR. That is why I had to have a false passport. My identity had to be secret.’

Haut frowned. This prompted her to add, ‘My father has many enemies. Enemies of the state.’

Haut had questions. Burning in his mind now was Cavalier’s cautioning that he could have been caught in a honey trap. Yet he was still in denial over the possibility.

‘There is something else,’ Natalia said, struggling to speak. ‘My father and mother are very close friends with President Putin.’

Two previous comments from her, above all others, now took on a different perspective: ‘You were very, very hard to catch,’ and ‘I wanted to marry the smartest man in the world’.

Haut could not put his mind on anything else but Natalia’s health, but he would later reflect on her comments and ‘pray into it’ for answers.

‘There is one other thing,’ she said. ‘My father is a very, very wealthy man. I tell you this, so you know I never went after you for money.’ She managed a wan smile. ‘If anything it should be the other way round.’

Haut held and kissed her.