‘We were all in love. I’m afraid it’s no excuse.’

It occurred to me once more that it might be time to go; that we had overstayed ourselves. There was no air in the school. No ventilation. ‘What did you two argue about? You were the best of friends, then nothing.’

‘Walter had started to be stingy with the coke,’ said Franz.

‘Really?’

‘At one point he even asked me to pay. I was hardly going to pay when I knew he got it for free. It was a minor disagreement, but he seemed to go off me.’

Walter had never been anything less than generous to me and Charlotte, and I wondered, finally, whether Jenö had been right: maybe the cocaine had been administered to Charlotte in the hope that it would put distance between those two.

‘He could take offence,’ I said. ‘But he was quick to forgive.’

Franz looked at me and smiled. We both knew this was not true. Walter could take an age to forgive. Franz snapped the novel shut.

‘How’d you patch things up? I saw you dancing at the Metal Ball.’

‘I started doing his homework for him.’

‘Ah,’ I said. ‘Well, there we are. Walter was ever the strategist.’

It was tricky to know what to do with my feelings. What he’d done to Charlotte, and to all the others who’d been caught in the Survey, was reprehensible, but it didn’t stop me missing him. I had no other confidant. Irmi and Kaspar were in Berlin. I couldn’t talk to Jenö; nor could I talk to Charlotte.

Often that spring I thought I heard him pottering around in his room, or I’d go out onto my balcony half expecting to see his face upside down, asking me to come up for a drink, or dangling a knotted bed sheet toward me. I missed my friend. I missed having someone to talk to.

Several letters arrived. The paper was smeared with Walter’s inky hand; maybe he was drunk or high when he’d written them. I wondered if he penned them in Ernst’s studio. Weimar was the same, he wrote; though there were now enough Brownshirts to give Dessau a run for its money. I know Charlotte reported me – he wrote – hardly a surprise, I suppose: she had just cause.

I wanted to reply but I didn’t know what to say. Slowly, anyway, I was able to put away my feelings for him, and what he had done hardened inside me. And, very soon, the betrayal felt insurmountable, and it became unthinkable that I would even consider replying.