‘According to eyewitness reports,’ Gessen said, consulting the file, ‘you attacked a man at the back of the lecture hall. He was badly injured and taken to hospital by ambulance.’ For now, Gessen would not tell Vidor the man had died. It would only make things worse, and as Vidor’s doctor, his first job was to address two questions: what caused him to attack a stranger, and what was the chance he would do it again?

‘Attacked a man—?’ Vidor leapt clumsily to his feet. ‘Preposterous. I’ve never harmed anyone in my life.’

Faced with Vidor’s sudden anger and spluttering denials, Gessen felt again a wave of déjà vu. A conviction, stronger now, that the two of them had met before. There was that medical conference on Neurology and Psychiatry in Paris a few years back. Could they have passed each other in the congress centre or stood in the same queue at the coffee bar?

Gessen had downloaded from the internet the scant information on Vidor he could find. A refugee from the 1956 Hungarian uprising, who’d spent his childhood in Paris before moving to the UK to attend university. Gessen had lived in Paris during his student years at the Sorbonne. Their paths could have crossed while Vidor was in the city between terms. A student cafe, a film festival, or simply passing each other in the street. Whatever it was, he couldn’t shake the feeling they had met somewhere before.

‘Please sit down, Vidor.’ Gessen smiled, hoping to return their discussion to an even keel. ‘You don’t mind if I call you Vidor, do you? It will facilitate our work together if I can address you by your first name.’

‘Our work together?’

In the silence that followed, Vidor fiddled with the black plastic strap on his wrist. Ursula would have explained it was an electronic monitoring device required of all the patients, but perhaps that detail, along with his other memories, had failed to stick.

He met Gessen’s eyes. ‘Am I a prisoner here?’

‘A prisoner? Whatever gave you that idea?’

Vidor pointed at the black wrist monitor and his clinic-issued clothing.