She flipped through the pages of photos, mainly variations of Eveline and her friends, or snaps of Paris monuments and street scenes. ‘This might be useful.’ She drew closer to the lamp. ‘It was taken at the introductory reception for international students. There were only eleven girls in our year, I believe. The dark-haired girl next to me was from Chile. Teresa, I think her name was. And that’s you, right?’ She passed the album to Gessen.

He stared at his own face, pasty and thin, and winced at the untidy mass of wavy hair, bell bottom denims and loud plaid shirt. How ridiculously young he was. Barely cooked, though his mind had been on fire, desperate to inhale great gulps of knowledge, like a starving man stuffing himself with delicacies. Still innocent, when the photo was taken, of the secret that would send him to the brink of hell.

He scanned the faces of the other boys, hoping one of them would spark something in his brain. That they all looked nearly identical didn’t help. Those wide-lapelled shirts and dungarees, the same mop of straggly hair. Mick Jagger look-alikes.

In the third row, on the left, a boy looking away from the camera seemed vaguely familiar. During his first year at the Sorbonne, Gessen had known all these students, at least by sight. But never a social butterfly, he’d attended at most one or two of the get-togethers for the foreign students. Painfully shy in those days, he was interested in books and learning, not parties. He flipped the page.

Eveline leaned against his shoulder. ‘I think that’s the end-of-term party for the first years. I didn’t go to any more after that, mostly because I wanted to fit in, not be set apart as a foreign student.’

The light was poor and most of the students in the photo appeared loopy with drink or exhaustion from having survived exam week. Had he gone to that party? He couldn’t remember now. His first year was a blur, arriving in the city full of hope, only to feel like a fish out of water amongst the sophisticated French. It hadn’t helped that he was out of sorts, having left Switzerland rather abruptly. After arguing with his adoptive parents about their reluctance to talk about his real mother and father, or how he’d come to live with them.

But in this shot, there was one boy who could be the same as in the group photo, the one who’d turned his face away from the camera. In the party photo, the boy’s gaze was directed at something behind the person taking the picture. With his hair pushed back, and his face turned away, the line of his forehead was clear, as was the shape of his nose. Was this the boy he was thinking of, the one who flicked his ear in the lecture hall?