Lately, there had been many occasions when the complex tangle of Fiona's working life became too much for her. She was using tranquillizers and sleeping tablets with a regularity that she'd never needed before. Bernard had found her crying several times when he'd come into the house unexpectedly. She had told him she was under treatment from her gynaecologist; embarrassed dear old Bernard had not pursued it further.

When she found herself weighed down by her thoughts, and the worries would not go away, Fiona found an excuse to leave the office and walked to the Waterloo mainline railway station. She'd come to like it. Its size suggested permanence while its austere design and girder construction gave it anonymity: a vast waiting room made from a construction kit. Coming through the dirty glass of its roof the daylight was grey, dusty and mysterious. Today – despite the rain – she had benefited from the walk from the office. Now she sat on a bench near number one platform and quietly cried her heart out. No one seemed to notice these emotional outbursts, except once when a lady from the Salvation Army offered her a chance for prayer at an address in Lambeth. Sobbing was not so unusual on Waterloo Station. Separations were common here and nowadays it was a place where the homeless and hungry were apt to congregate. London Airport was probably just as good a place to go for the purpose of weeping, but that provided too great a chance of seeing someone she knew. Or, more exactly, of someone she knew seeing her. And Waterloo Station was near the office, and there were tea and newspapers, taxi-cabs and metered parking available. So she went to number one platform and cried.

It was the prospect of leaving Bernard and the children, of course. They would end up hating her. Even if she did everything that was expected of her, and returned a heroine, they would hate her for leaving them. Her father would hate her too. And her sister Tessa. And what would happen to the children? She had asked Bret that, but he had dismissed her fears. The children would be cared for in the manner that her sacrifice and heroism deserved, he'd said in that theatrical style that Bret could get away with because he was so damn certain. But how sincere was he? That worried her sometimes. Sincere or not she couldn't help thinking that her children would be forgotten once she was working in the East. Billy would survive boarding school – and perhaps even flourish there – but Sally would find such an environment unendurable. Fiona had resolved not to put her children through the sort of childhood that she had hated so much.

Bret told her that the only thing that frightened her more than the prospect of finding that her husband and children wouldn't be able to manage without her, was the prospect of finding that they could. Bastard! But perhaps there was a glimmer of truth there. Perhaps that was the permanent crippling dilemma that motherhood brought.

She had never been a very good mother and that knowledge plagued her. She'd never wanted motherhood in the way that her sister Tessa so desperately did. Fiona had never liked babies: her friends' babies had appalled her with their endless demands and the way that they completely upset the households. Babies cried very loudly; babies vomited very frequently and dirtied their nappies very stenchfully. Even when hugging her own babies she had always been uneasy in case her dress was soiled. The children's nurse had seen that right from the start, and Fiona still remembered the accusing look in her eyes. That look said, I am their real mother: you are not fit to look after them.

Fiona was useless with children but she didn't want to be barren either. She wanted to tick motherhood off the list. She worried about them always, and wanted them to be clever at school, and most of all she looked forward to sharing their lives with them when they grew up. But it was now that they needed her so much. Perhaps it was not too late. Perhaps she should walk out of London Central and apply herself to the children as she had applied herself to her studies and her work.

Never a day went past but she told herself that she should go to Bret and tell him she had changed her mind. But each time she spoke to him – long before she could bring the conversation to the point she wanted – he persuaded her that her first duty was to her country and the Department. Even the Director-General had spoken with unusual gravity about this scheme to get her into position as a field agent, a field agent of prime importance. It would, of course, show that women could bring off an intelligence coup as well as any man. That, more than anything else, had helped her keep going when her spirits were low.

Since the beginning of the year her tiffs and differences with Bernard had multiplied. It wasn't all Bernard's fault, things had been difficult for him too. Operation 'Reisezug' had been something of a disaster: three of their own people killed, or so the rumour said. Max Busby was carrying a lot of the material in his memory and Max never came back.

Bernard didn't talk about it but anyone who knew him could see how shaken he was.

Bernard was now officially 'rested' from field work and, in what might have been an effort to comfort her, Bret Rensselaer had let slip the fact that the Department had decided that Bernard should spend the rest of his life behind a desk. Not the German Desk. Dicky Cruyer-a vain and shallow man – had got the German Desk. Bernard was in line for it and would have done it with more skill and intelligence, but Dicky had the administrative experience as well as the personality and background that the Department favoured for top jobs. Bernard said that all Dicky had was the right old school tie, but Bernard could be a bit touchy about such things. She'd wondered if Bret decided against Bernard's promotion because of her assignment, but Bret insisted that it was a decision made at the top.

She was sure that her painful domestic life could be transformed if Bret would let her confide in her husband. As it was she couldn't always account for her movements. It had been bad enough when she'd only had to have the odd meeting with Martin Euan Pryce-Hughes. Now there were countless covert briefings by Bret and a lot of studying to do. And the studying was of material that she mustn't let Bernard catch sight of. Bernard was smart and quick. She wouldn't have to make many mistakes for him to guess what was happening, and the D-G had taken it upon himself to tell her that if Bernard discovered what was planned the whole thing was off.

Poor Bernard; poor Billy; poor Sally. She sat on the bench at Waterloo and thought about them all. She felt drained and ill. Crying released the tension within her but it did nothing to alleviate the pain. She cried some more in the constrained, unobtrusive and dignified way she'd learned to cry at boarding school, and stared across the concourse where people were hurrying for their commuter trains or saying their farewells. She told herself that their troubles might be worse than hers but that did nothing to help: in fact it made her feel even more dejected.

The weather did nothing to cheer her. It was one of those miserably cold and rainy days that so often punctuate an English summer. Everyone was bundled into coats and scarves and the cold damp air contributed to Fiona's chilly gloom. Trains arrived; trains departed. A young woman wanted to know the time, and an elderly couple walked past arguing vociferously. Pigeons and sparrows came gliding down from the girders of the roof, encouraged by a bearded man on a bench nearby who threw crumbs to them. She sat there watching the birds for what seemed a long time.

'Pardon me, madam.' Fiona looked up to see two men: a uniformed railway policeman and a man in civilian clothes. 'You were talking to a young woman a few minutes back?' It was the policeman who spoke.