It must have been ten times over the course of the next hour that I got up to leave, before losing the courage even to walk out the door. Finally, I decided for certain that I was making a terrible mistake and picked up my bag to go. At that moment, however, a man strode into the room – bald, but quite handsome despite it, and my heart sank. Instantly I was back in that cage, the smog seeping into the dark van as we wound through traffic, the smell of his breath and sweat. I had hoped never to see Grest again, but my name must have been linked with his in the files. He stopped and looked around the lobby, then came over to me. ‘Mrs Cawson.’

I stared at him. ‘I’m sorry, I’ve –’

‘Come this way,’ he said, as he led me towards two doors guarded by Secs with gun holsters.

‘No, I was –’

‘Come this way.’

His shoes clipped on the floor as he recorded my entry at the guard post. In the corridors on the other side, everyone had the same look of grim determination, as if we were still at war and the enemy were expected to land at any moment. I had to keep up with his pace, until he stood back with formal politeness to let me enter a plain room. The door was thick enough to prevent any sound passing through it.

I sat at the small table, trying not to think of the other featureless rooms in this building and what took place in them. Somewhere, Nick sat or lay. If he knew I was there, he might have felt some comfort or simply more fear. ‘My husband,’ I said, trying to speak with strength but finding that strength dissolving.

‘Yes.’

‘He’s innocent.’ Grest just snorted. I could see he was wondering what my plan was. Simple pleading? Vehement denials? Supply some rumour about Nick’s friends in return for favour? He had probably heard it all a hundred times. ‘Well, he’s not entirely innocent. He’s committed a crime but it’s not what you think.’ Now he looked mildly interested. ‘You think he and Lorelei were working for the Americans. They weren’t. Please. Read this.’ I reached into my pocket and pulled out the letter I had taken from the stack in Nick’s writing desk. I didn’t want to think what would happen – to him, to me – if I were wrong.

Lorelei’s letter told of the American colonel who, she suggested, was in a more underhand section of the army than the Education Corps to which he claimed allegiance. But before she wrote of him, she had described some of the other guests at the party – and one in particular: