'Overseas?'

'You know Washington; you like Americans.'

'Lots of people want to go to Washington,' I said to gain time. 'Who knows when a vacancy will come.'

Moskvin continued to play with the clips. ' Washington gossip says London Central will fill two vacancies in the next month or two. Two senior jobs – that's what our Washington office tells us.'

Through the blur of pain my memory said he was right: sickness and a promotion had created two unexpected vacancies in the Washington Embassy. I'd seen the signal on Bret's desk. I was senior enough to apply for either. 'No,' I said.

'Think about it,' said Moskvin. Under his silky voice I could hear the hatred and contempt that he was trying to hide.

'Or what?'

'No threats,' said Moskvin. 'But surely it would be more civilized?'

'More civilized than staying in London to undo some of the harm of my wife's treachery?'

'Be more sophisticated and less arrogant, Herr Samson. Can you really believe that your contribution to the work at London Central will make any difference?'

I shrugged – but it hurt.

'What are you trying to prove, Samson? We've got an operations file on you that's that thick.' He indicated with finger and thumb. 'And that's without all the dangerous tricks you've done undetected. How long can you go on trying to prove you're a field agent? Until you get yourself killed, is that it?'

'You wouldn't understand,' I said.

'Because I'm a desk man?' He almost lost control over his rage. 'Vanity, is that it? Prove yourself over and over again so you can be sure you're not a coward? Just as the repressed homosexual becomes a womanizer to prove he's really a man?' Was that some reference to his ex-colleague Stinnes? If it was, he gave no further evidence of it. He put away his playthings and stood, hands on hips, his long black greatcoat open to reveal an ill-fitting grey suit and dark roll-neck sweater. He looked like someone who'd dressed in response to a fire alarm.

'Start life again, Herr Samson. Forget the pain of the past.' He saw me glance towards the door. 'What do I have to do to persuade you?' He smiled and I could see the sadistic glee in his face. He knew I'd seen into the next room.

'I'll think about it,' I told him. Was Billy still there, I wondered? It was torture carrying on this conversation.

'Don't think about it,' said Moskvin softly. His voice rose to a shout as he added, 'Do it!'

'I said I'd think about it.'

'Then think about this too,' he yelled. He snatched the door open and stood in the doorway. With hands cuffed, I'd stand no chance against him – he'd already proved that. But I pushed close to see over his shoulder.

'Billy!' I called but the bundled figure made no response. 'Why drug the child?' I said. I couldn't keep the weariness and defeat from my voice. The doctor and nurse had gone. Even the disinfectant, the hypodermic and the enamel tray had gone. 'Where's the doctor?' I asked.

'Doctor?' said Moskvin. 'What doctor? Are you mad?' He went striding across the room to the bunk bed. 'Think about this, Samson,' he yelled over his shoulder. He raised his arm, his massive fist clenched over the bed.

'No, don't!' It was a plea now, the fight had gone out of me. But he paid no heed to my call. His punch almost broke the wooden frame of the bed, with such force did it descend. The terrible blow swept everything across the room: blankets, the pathetic wollen hat, the boots and anorak. It all clattered to the floor in a heap.

Moskvin laughed. 'What did you think, Samson? Did you think we had your son in here?' Now I could see that these were not Billy's clothes: just clothes like them.

I leaned against the wall. I felt the bile rising in my throat. I closed my lips tight, determined not to give him the satisfaction of seeing me throw up. But it was not possible. I leaned forward and vomited my breakfast across the floor along with a generous measure of Mrs Koby's homemade wine.

Moskvin really laughed then. It was the first spontaneous human reaction I'd ever seen from him. He unlocked my handcuffs. 'We'll get a car and take you back to the West, Samson. Where would you like to go, Frau Hennig's hotel?'

I nodded and used a handkerchief to wipe my face and my clothes. The sweet-sour smell of the vomit was in my nostrils.

'You'll need to wash and change,' said Moskvin. 'But you just remember this, clever Mr Field Agent: any time we want you, we'll pick you up as easily as we did today. And not just you, Samson; your children, your mother, your friend Volkmann… any time we want you. You remember that, my friend.' He laughed again. I could hear him laughing as he marched off down the corridor and shouted for the driver. I looked back at the TV monitor. Was Fiona watching? And did she feel proud of herself?

When I got back to Tante Lisl's I took a long hot bath and examined my cuts and bruises. Then I changed my clothes to take Lisl to the Volkmanns' for what we both thought was to be a quiet sit-down meal. We were wrong.

It was a ferocious event; the sort of frantic party you find only in Berlin and New York. The hi-fi was playing 'Hello, Dolly!' as I went in, and the guests were in that restrained sort of fancy dress that provides a chance to wear jewellery and expensive hair-dos. It was noisy and crowded and the air was blue with tobacco smoke and there was the fragrance of French perfumes and Havana cigars.

Tante Lisl showed little surprise at the mad scene to which I'd brought her. She'd brought up little Werner after his parents died, and she felt for him that compassionate condescension that motherhood brings. She sat in the corner on the thronelike chair that Werner had thoughtfully placed there for her. She sipped her champagne and surveyed the antics of the guests with a wry superiority, like a tribal chief watching the sort of ceremonial dances that end in human sacrifice. She'd prepared carefully for the party: false eyelashes and real pearls; Tante Lisl's ultimate accolade.

I went to the buffet table in the dining room to assemble a plate of food for her. The room, like every other room in the apartment, was crowded. In front of me there was a tall thin Mephistopheles. He was engaged in earnest conversation with a man in a white-silk roll-neck sweater. He said in uncertain English, 'We Germans are so very like you Americans! That's why there is this constant friction. Both our countrymen respond to ideology, both seek always to improve the world, and both often want to improve it by means of military crusades.'

'And both like clean toilets,' said the American in the roll-neck sweater. ' Germany is the only goddamned country in Europe that doesn't have filthy bathrooms.'

'Anal oriented, we psychiatrists say,' Mephistopheles told him. 'In other countries people just want to get in there, do what has to be done, and get out again as soon as possible. But you Americans and we Germans like to have toilets we can spend time in. One glance in any of these home-improvement magazines will confirm that.'

A movement of the crowd around the buffet allowed me to push forward to the table near the window and reach the stack of empty plates and silverware. I looked round me. Only in Berlin would they have a party like this in daylight. Outside it was gloomy, but to the west there was even a little sunlight breaking through the clouds. The food was disorienting too. It was not exactly what I'd think of as Christmas Day lunch, but it was a magnificent display of luxuries. Although a great deal had already been eaten, new plates of food kept appearing, brought by waitresses in neat black dresses and fancy lace aprons. This was a Fresserei, a feast where people gobble like animals. There were lobster tails in mayonnaise and crab claws in wine sauce. There was caviar and cold salmon, foie gras with truffles, and a dozen types of sliced sausage.