It was clear he had no memory of what preceded his collapse in the swimming pavilion. When Gessen questioned Babette, who’d witnessed the whole thing, she’d been quite voluble in her description of Vidor’s condition, as if he’d taken some kind of turn. His face had contorted, and his eyes rolled back in his head. It could have been a temporal lobe seizure. Or a garden-variety migraine, perhaps, though Vidor hadn’t mentioned any prior history. But such episodes seemed to be occurring more frequently. Babette was lucky he hadn’t attacked her as he had the man in Copenhagen and the one in the village. Though she may have found the whole episode exciting, and a source of new symptoms to add to her long list of ‘mystery ailments’. His patient for three months now, Babette’s Munchausen’s was proving particularly difficult to treat.

Vidor probed at the skin above his ear. Was he feeling something odd there? In rare cases temporal lobe seizures could result in violence. A possible diagnosis to add to the mix. He made a mental note to have Vidor undergo a seventy-two-hour electroencephalograph.

‘I can give you something for the pain if you like.’

He shook his head. ‘A nurse gave me some tablets that knocked it out. I’m still feeling woozy, but that will pass, no doubt.’

‘A game is just what you need then,’ Gessen said, ‘to get your mind off things. We can have our session later, if you prefer, but a friendly round of chess will get the blood flowing to your brain again.’

Vidor perched on the edge of the chair, hands clasped in his lap, docile as a child. Gessen tried not to stare openly as he attempted to parse Vidor’s state of mind. He looked befuddled and drained. Had something happened in the night? Another bout of sleepwalking or strange dreams? The frequency of nocturnal disturbances had shot up in the last few days. While exhausting for Vidor, it was a positive sign that his boundaries were beginning to dissolve. In this weakened state, his alter, if he were in there, was more likely to show his face. Tired, malleable, confused, Vidor might finally release the iron grip on his inner demons.

They faced each other across the chessboard. No fire was lit in the hearth today. Though Gessen normally relished the warmth and sound of a crackling fire, he didn’t need the distraction. Now that he was closing in on Vidor’s defences, it was important to stay focused.

Vidor moved his pawn in a classic opening manoeuvre. Gessen scanned the board, already several moves ahead. He checked his watch, hoping to reach checkmate in thirty minutes or less. Three moves in and his strategy seemed to be working.

Vidor swayed in his seat. ‘What is that smell?’ He wrinkled his nose as if faced with something putrid.