‘Not yet.’ Gessen slipped the letter in his desk drawer and locked it. ‘You don’t mind if I keep this, do you? The date of Vidor’s “experiment” could just be a coincidence, and there’s no reason to suppose that he didn’t spend the day in his room as he claimed. Even without his wrist monitor as proof.’

‘But how can we—?’

‘I’m not going to lie to the police,’ Gessen said, cutting her off. ‘But first I’d like to question Vidor myself. If he comes clean about the whole “brain-wave experiment”, he probably has nothing to hide. If he doesn’t…’ His unvoiced thought hung in the air between them. Ismail’s fall might not have been an accident.

* * *

Pellets of ice clattered against the window. Not yet three o’clock but the lamps were already lit. One of the dining room staff carried a tray of tea and biscuits into the room and set it on the table by the fire. Vidor eyed the buttery ovals topped with slivered almonds and caramelised sugar.

‘Winter has come to stay,’ Gessen said in an annoyingly cheery voice. ‘The mountains cloaked in snow, the air shimmering like glass. My favourite season.’ He passed Vidor the plate of biscuits. ‘Do you ski?’

Vidor shook his head. He felt heavy and dull, like a tranquillised bear.

‘I was in Paris recently,’ Gessen said in what seemed like a complete non sequitur. ‘A lovely city. After attending an interesting seminar, I met up with some former school chums. We talked about old times, as one does on such occasions. Laughing at the folly of youth and the wild dreams we once had. Our loves and our sorrows.’

‘What is that smell?’ Vidor pressed a napkin to his nose.

‘Almonds and cinnamon, from the biscuits, I believe. Why, does it bother you?’

‘No.’ He hesitated. ‘It’s just that I’m not particularly fond of almonds. Poppy seed cake was what my mother used to make on Sundays. An old family recipe and a favourite of mine.’

Gessen raised his eyebrows, as if waiting for Vidor to expand on this particular memory. But Vidor had been feeling odd all day and was in no mood to oblige.

‘My friends and I got to talking about our days at the Sorbonne as foreign students and how excited we were to be in Paris,’ Gessen was saying as he nudged the plate of almond biscuits across the table. ‘Somebody asked me if I remembered this one particular boy. Very shy, he was. From somewhere in the Balkans, I believe. Or perhaps the Middle East.’

Vidor gave him a blank look.