'He's spying on you,' said Werner, in a voice of feigned weariness. 'How long is it going to take before you start believing me?'

Zena reappeared with a tray upon which stood my slice of apple strudel, whipped cream, the coffee and a small plate of assorted chocolates. 'Who was on the phone?' she asked.

'Frank Harrington,' said Werner. 'He wanted Bernie.'

She nodded to show she'd heard and she arranged the things from the tray on the table. Then, when she'd finished her little task, she looked up and said, 'They're offering Erich a quarter of a million dollars to defect.'

'What?' said Werner, thunderstruck.

'You heard me, darling. London Central are offering Erich Stinnes a quarter of a million dollars to defect.' She was aware of what a bombshell she'd thrown at us. I had the impression that her main motive in persuading me to stay to dinner was to have me present when she announced this news.

'Ridiculous,' said Werner. 'Do you know anything about that, Bernie?'

Zena gave me no chance to steal her thunder. She said, 'That is a gross sum that would include his car and miscellaneous expenses. But it wouldn't be subject to tax and it wouldn't include the two-bedroom house they'll provide for him. He'll be on his own anyway. He's decided not to ask his wife to go with him. He's not even going to tell her about the offer. He's frightened she'll report him. They don't get along together; they quarrel.'

'A quarter of a million dollars,' said Werner. That's… nearly seven hundred thousand marks. I don't believe it.'

Zena put the strudel in front of me and placed the whipped cream to hand. 'Do you want whipped cream in your coffee, Werner?' She poured a cup of coffee and passed it to her husband. 'Well, it's true, whether you believe it or not. That's what they've offered him.'

'I haven't heard anything about it, Zena,' I said. 'I'm supposed to be handling the whole business but I've heard nothing yet about a big lump sum. If they were going to offer him a quarter of a million dollars I think they'd tell me, don't you?'

It was intended as a rhetorical question but Zena answered it. 'No, my dear Bernard,' she said. 'I'm quite sure they wouldn't tell you.'

'Why not?' I said.

'Use your imagination,' said Zena. 'You're senior staff at London Central, maybe more important than a man such as Stinnes…'

'Much more important,' I said between mouthfuls of strudel.

'Exactly,' said Zena. 'So if Erich is worth a quarter of a million dollars to London Central you'd be worth the same to Moscow.'

It took me a moment or two to understand what she meant. I grinned at the thought of it. 'You mean London Central are frightened in case I discover what I'm worth and then defect to Moscow and price myself at the same fee?'

'Of course,' said Zena. She was twenty-two years old. To her it had the elegant simplicity that the world had for me when I was her age.

'I'd need more than a quarter of a million dollars to soften the prospect of having to spend the rest of my days in Moscow,' I said.

'Don't be evasive,' said Zena. 'Do you really think that Erich will spend the rest of his days in London?'

'You tell me,' I said. I finished my strudel and sipped at my coffee. It was very strong. Zena liked strong black coffee but I floated cream on mine. So did Werner.

Werner rubbed his face and took his coffee over to the armchair to sit down. He looked very tired. 'You can see what Zena means, Bernie.' He looked from me to Zena and back again, hoping to find a way of keeping the peace.

'No,' I said.

'Extending this idea just for the sake of argument,' he said apologetically, 'Moscow would simply want to debrief you in depth. What are we talking about: six months? Twelve months at the outside.'

'And after that?' I said. 'Continuing to extend this for the sake of argument, what would happen to me after that?'

'A new identity. Now that the KGB have that new forgery factory near the airport at Schönefeld they can provide papers that pass damned near any sort of scrutiny. German workmanship, you see.' He smiled a tiny smile; just enough to make it all a bit of a joke.

'German workmanship,' I said. The Russians had been at it since 1945. They'd gathered together the scattered remnants of SS unit Amt VI F, which from Berlin's Delbruckstrasse – and using the nearby Spechthausen bei Eberswalde paper factory, and forgers housed in the equally nearby Oranienburg concentration camp – had supervised the manufacture of superb forgeries of everything from Swedish passports to British five-pound notes. 'Perfect papers and a new identity. Plus an unlimited amount of forged paper money. That would be lovely, Werner.'

Werner looked up from under his heavy eyelids and said, 'Defectors to Moscow wind up in weird places, Bernie. You and I both know certain residents of Cape Town, Rome and… where was that last one: some place in Bolivia?… who have changed their names and occupations suddenly and successfully since the last time we saw them.'

'For a quarter of a million dollars?' I said. 'And spend the rest of your life in Cape Town, Rome or Bolivia?'

'Zena didn't mean that you'd do that for a quarter of a million dollars, Bernie.'

'Didn't she? What did you mean, Zena?' I said.

Zena said, 'No need to get touchy. You heard what I said, and you know it's true. I said that London Central were afraid of what you might do. I didn't say that I felt the same way. London Central trust no one. They don't trust Werner, they don't trust you, they don't trust me.'

'Trust you how?' I said.

Zena touched her necklace and smoothed the collar of her silk jacket, preening herself while looking away across the room as if half occupied with other, more important matters. 'They don't trust me to be their contact for Stinnes. I asked Dicky Cruyer. He ignored the question. Earlier this evening I put the same idea to you. You changed the subject.'

'Do you know for certain that Erich Stinnes has only the one child?' I said.

'Not a child exactly,' said Zena. 'He has just the one son who is eighteen years old. Perhaps nineteen by now. He failed to get into Berlin University last year in spite of having very high marks. They have a system over there that gives priority to the children of manual workers. Erich was furious.'

I got up from the table and went to look out of the window. It was dusk. Werner's apartment in the fashionable Berlin suburb of Dahlem looked out on to other expensive apartment blocks. But between them could be seen the dark treetops of the Grunewald, parkland that stretched some six kilometres to the wide water of the Havel. On a sunny day – with the windows open wide – the sweet warm air would endorse every claim made for that famous Berliner Luft. But now it was almost dark and the rain was spattering against the glass.

Zena's provocative remarks made me jumpy. Why had London not told me what they'd offered to Stinnes. I wasn't just the 'file officer' on a run-of-the-mill operation. This was an enrolment – the trickiest game in the book. The usual procedure was to keep 'the enroller' informed about everything that happened. I wondered if Dicky knew about the quarter of a million dollars. It took no more than a moment to decide that Dicky must know; as German Stations Controller he'd have to sign the chits for the payment. The quarter of a million dollars would have to be debited against his departmental outgoings, until the cashier adjusted the figures by means of a payment from central funding.

Street gutters overflowing with rain-water reflected the street lamps and made a line of moons that were continually shattered by passing traffic. Any one of the parked cars might have contained a surveillance team. Any of the windows of the apartment block across the street might have concealed cameras with long-focal-length lenses, and microphones with parabolic reflectors. At what point does sensible caution become clinical paranoia. At what point does a trusted employee become 'a considered risk', and then finally a 'non-critical employment only' category. I closed the curtains and turned round to face Zena. 'How furious?' I said. 'Is Stinnes furious enough to send his son to university in the West?'