'A mighty victory?' she said mechanically.

'I told you before; the economic projections suggest that we could make them knock the Wall down, Fiona. A revolution without bloodshed. That would go into the history books. Literally, into the history books. Our personal affairs count for nothing against that.'

He knew everything she wanted to hide; she could see it in his eyes. 'Are you blackmailing me, Bret?'

'You are not yourself tonight, Fiona.' He feigned concern but without putting his heart into it.

'Are you?'

'I can't think what you mean. What is there to blackmail you about?'

'I don't respond to threats; I never have.'

'Are you going to tell me what I'm supposed to be threatening you about? Or do I have to start guessing?' Fiona could see he was loving it; what a sadist he was. She hated him and yet for the first time ever she saw within him some resolute determination that in other circumstances might make a woman love him. He would fight like this on her behalf too; there was no doubt about that. It was his nature.

'Answer one question, Bret: are you having me followed?'

He put down his fork, leaned back in his chair, clasped his hands with interlocked fingers, and stared at her. 'We are all subject to surveillance, Fiona. It's a part of the job.'

He smiled. She took her glass of champagne and tossed it full into his face.

'Jesus Christ!' He leapt to his feet spluttering and fluttering and dancing about to dab his face and shirt-front with the napkin. 'Have you gone ape?'

She looked at him with horror. He went across the room to get more napkins from a side table. He dabbed his suit and the chair and as his anger subsided he sat down again.

She hadn't moved. She hated to lose control of herself, and rather than look at him she picked up her fork and used it to follow a blob of souffle across her plate. 'But Bernard doesn't know?' she said without looking up. She didn't eat the piece of souffle: the idea of eating was repugnant now.

He ran a finger round inside his collar. The champagne had made it stick to the skin. 'Such housekeeping is done outside the Department. It would be bad security to use our own people.'

'Promise me that Bernard won't know.'

'I could promise that he won't be told by me. But Bernard is a shrewd and resourceful man… I don't have to tell you that.' He looked at his watch. He wanted to go and change.

'It's all finished anyway.'

'I'm glad.' He looked at her and – despite the wet stains on his shirt and his disarranged hair – he gave her his most charming smile.

'You know what I'm talking about?' she asked.

'Of course not,' he said, and kept smiling.

'It's clearly understood that I'm over there for only a year and then I must be pulled out?'

'A year. Yes, that was always the plan,' said Bret. 'Have you got a purse? I'll give you the details of the intercept. Phone the contact number for Pryce-Hughes first thing tomorrow. It's his morning for being at the office number he gave you.' Even being doused with champagne had not unnerved him.

'You're a cold-blooded bastard,' she told him.

'It never was a job suited to hot-blooded people,' said Bret.

London. April 1983.

For Bret Rensselaer that long long ago dinner in Berlin was a hiccup in the lengthy preparation that Fiona Samson had undergone for her task. Looking back, it was just a chance for him to provide some of the comfort and reassurance that become necessary to agents when traumatic indecision attacks them. It had been, he told the D-G, in one of the reviews Bret liked to provide, an inevitable stage in the briefing and preparation period of any long-term agent placement. 'It was a role change for her. Some would call it the "schizothymic period", for we had to inflict upon a normal personality the task of becoming two separate ones.'

The D-G was about to challenge both the terminology and the scientific basis of what sounded like a distorted over-simplification, but just in time he remembered a previous discussion in which Bret – who had been psychoanalysed – buried him under a barrage of psychological doctrine which had included extensive notes, statistics and references to 'the fundamentally important work of James and Lange'. So the D-G nodded.

Bret reminded him that in this case the agent was a woman, a highly intelligent woman with young children. Thus the attack had been more acute than usual. On the other hand, these factors which made her vulnerable to doubts and worries were the same elements which would make her less suspect when she went to bat for them. Fiona Samson was a stable personality, and Bret's subtle conditioning had reinforced her behaviour, so that by the time she was 'put into play' Bret was confident that the 'transference' would be complete. Since that awful champagne throwing scene an emotional dependence upon Bret, and thus upon the decisions made in London Central, had provided her with the necessary motivation and internal strength of mind.

'You know far more about these things than I do,' declared the D-G with a genial conviction that did not reflect his true feeling. 'But my understanding was that in a scientific context "transference" sometimes means the unconscious shifting of hatred, rather than love and respect.'

'Entirely true!' said Bret. Jolted, not for the first time, by the old man's sharpness, he recovered quickly enough to add, 'And that's an aspect of the work that I have already taken into account.'

'Well, I'm sure you have everything under control,' said the D-G, looking at his watch.

'I do, Director. Depend upon it.'

Bret Rensselaer was not basing these conclusions upon his personal experiences with field agents; he'd had little personal contact with those strange animals in the course of his career (although of course the day-to-day decisions he'd made had had an effect upon the whole service). The Director-General was well aware of Bret's purely administrative background. He'd chosen him largely because he had no taint of Operations on him – and no one had guessed that a dedicated desk man like Bret could function as a case officer – and thus Fiona's role of double agent would be more secure.

But Bret Rensselaer, and Fiona Samson, were not the only ones coping with the problems of the role change. For if Fiona had never been an agent before, and Bret had never been a case officer, it was also true that the D-G had never before faced the harrowing experience of sending into enemy territory someone he knew as well as he knew Fiona Samson. However it was too late now to change his mind. The D-G allowed himself to be comforted by Bret's optimistic reassurances because he could think of no possible course of action if he became anxious.

If that long ago dinner at Kessler's was remembered by Bret as no more than a temporary failure of Fiona's resolution, it was burned into her memory as a program is burned into a micro-chip. She remembered that horrifying evening in every last humiliating detail. The condescension with which Bret Rensselaer had treated her desire to pull out of the operation, the insolent way he had so smoothly blackmailed her into continuing. The contempt he'd shown for her when she'd thrown the champagne: humouring her as one might the infant daughter of a respected friend. And, most shaming of all, the way in which she had done exactly what he told her to do. For, like so many humiliations, hers was measured by the success of the opposing party: and Bret's dominance by the end of that dinner had been absolute.

From that dire confrontation onwards, she had never again expressed any desire to withdraw from the task ahead. After those first few agonizing weeks during which she desperately hoped that Bret Rensselaer would leave the Department, be transferred or suffer a fatal accident, no idea of being released from her contract entered her head. It was inevitable.