He left the room with me. A second later the clip ended. The footage lasted three minutes, twenty-five seconds in total.

I remember most rooms, let alone most individuals I’ve shared them with. I’d never been in that room or met that man. I looked more closely at the shadows cast by objects, the movement of faces and hands: light reflections and skin texture. There was a mirror on a cupboard at the side with a crack across it. The reflections matched. I studied the architecture visible through the window: it looked like we were high up, in a modern skyscraper with a glimpse of an adjacent wing and the roof of a lower tier. The façade was ornamented. Neo-baroque spires fenced the rooftop off from the sky. It didn’t look Western, more like something you’d find in a former communist country.

I clicked back, watched myself again as I left. A triangle of light fanned out across the floor, two shadows disrupted it, then both were gone.

FIVE

‘Happy birthday.’

I imagined the chain of events behind this. Someone had come across the video file, illicitly or otherwise, and they felt I ought to see it. They wanted me to know I was passing through rooms I’d never been in. There were implications. They chose an ultradiscreet means of communicating: not via official channels; via a dead man’s code.

I took the wrapped box from the safe, unwrapped it and held the diamond in my palm. I closed my hand around it, then I tried Joanna’s number again. The silence was becoming loud.

Memory erodes from the inside out: beginnings and endings sharpen as the rest grows vague. My last glimpse of Joanna Lake was in a lorry drivers’ café on the M1, beside the Newport Pagnell motorway services area. She was following new security protocols. This was one of them: I couldn’t be seen within five miles of her workplace, which was a secure governmental facility with unique sensitivity.

We had spent a weekend together, shadowed by its own brevity and the dark unknown beyond it, ruined by a fight of unprecedentedly personal dimensions. I was heading back to Saudi Arabia, to live another life. She was heading back to a UK-based role she couldn’t tell me about.

We weren’t good at farewells, which aren’t easy when both of you are embarking into secrets. And it didn’t help when we tried to rescue the situation with promises we were trained not to believe in. This time, when we spoke about leaving the intelligence service I think we both meant it. We ended with a show of reconciliation but I had emailed twice in the intervening six months without reply.