'Right,' I said. 'So the chances are that Moscow know even more than the evidence suggests.'

'Do you think it could be me?' said Dicky. He beat a soft but rapid tattoo on his hand.

'It's not you,' I said. 'Maybe it's not anyone. Maybe there is no pattern of betrayal – just incompetence.'

'Why not me?' Dicky persisted. He was indignant at being dismissed so readily as a suspect.

'If you'd been a Moscow agent, you would have handled the office differently. You would have kept your secretary in that anteroom instead of moving her inside where she can see what you are doing all the time. You'd make sure you know all kinds of current matters that you don't bother to find out. You wouldn't leave top-secret documents in the copying machine and cause a hue and cry all round the building the way you did three times last year. A Moscow agent wouldn't draw that kind of attention to himself. And you probably would know enough about photography not to make such a terrible mess of your holiday snapshots the way you do every year. No, you're not a Moscow man, Dicky.'

'And neither are you,' said Dicky, 'or you wouldn't have brought it up in the first place. So let's stick together on this one. You're going to Berlin to contact the Brahms net. Let's keep your reports of.that trip confidential verbal ones. And from now on let's keep the wraps on Trent and everything we do, say or think about him. Between us, we can keep a very tight hold on things.'

'You mean, don't tell Bret?'

'I'll handle Bret. He'll be told only what he needs to be told.'

'You can't suspect Bret?' Immediately I thought of Fiona. If she was having an affair with Bret, any investigation of Bret would reveal it. Then there would be the very devil of a fuss.

'It can be anyone. You've said that yourself. It could be the D-G.'

'Well, I don't know, Dicky,' I said.

Dicky became agitated. 'Oh, I see what you're thinking. You think this might be a devious method of starving Bret of information. So that I can take over his job.'

'No,' I said, although that was exactly what had crossed my mind.

'Let's not kick off to a bad start,' said Dicky. 'We've got to trust each other. What do I have to do to make you trust me?'

'I'd want something in writing, Dicky. Something that I could produce just before they sentence me.'

'Then you'll do as I suggest?'

'Yes.' Now that Dicky had voiced my fears, I felt uneasy – or, rather, I felt frightened, bloody frightened. A Moscow agent in place endangered all of us, but if he was caught, maybe he'd leave the whole Department discredited and disbanded.

Dicky nodded. 'Because you know I'm right. You bloody well know I'm right. There is a Moscow agent sitting right at the top of the Department.'

I didn't remind Dicky that he'd started off by saying that it was my conversation with Bret that eventually made him see what I was getting at. It was better that Dicky thought it was all his own idea. Balliol men like to be creative.

There were footsteps and a knock at the door. The doctor came in. 'The patient is sleeping now, Mr Cruyer,' he said respectfully. Given the Victorian setting, I had expected a man with muttonchop whiskers and stovepipe hat. But the doctor was young, younger than Dicky, a wide-eyed boy, with long wavy hair that reached down to his stiff white collar, and carrying a battered black Gladstone bag that he must have inherited from some venerable predecessor.

'So what's the prognosis, Doc?' said Dicky. ' The doctor put his bag down on the floor while he put his overcoat on. 'Suicide is no longer the rare tragedy it once was,' he said. 'In Germany, they have about fourteen thousand a year, and that's more than die there in traffic accidents.'

'Never mind the statistics,' said Dicky. 'Is our friend upstairs likely to try again?'

'Look, Mr Cruyer, I'm just a GP, not a soothsayer. But whether you like statistics or not, I can tell you that eight out of ten suicides speak of their intentions beforehand. If someone sympathetic had been available to your friend, he probably wouldn't have taken this desperate step. As to whether he'll try again, if you give him the care and attention he obviously requires, then you will know what he's going to do long before any quack like me gets called in to mop up the mess.'

Dicky nodded as if approving the doctor's little speech. 'Will he be fit by tomorrow?' said Dicky.

'By the weekend, anyway,' said the doctor. Thanks to Miss Trent.' He moved aside to let Giles Trent's unmarried sister push past him into the room. 'Her time as a nurse served her well. I couldn't have done a better job myself.'

Miss Trent did not respond to the doctor's unctuous manner. She was in her late fifties, a tall thin figure like her brother. Her hair was waved and darkened and her spectacles decorated with shiny gems. She wore a cashmere cardigan and a skirt patterned in the Eraser tartan of red, blue and green. At the collar of her cotton blouse she wore an antique gold brooch. She gave the impression of someone with enough money to satisfy her modest tastes.

The furnishing of the room was like Miss Trent: sober, middle-class and old-fashioned. The carpets, bureau-bookcase and skeleton clock were valuable pieces that might have been inherited from her parents, but they did not fit easily there and I wondered if these were things Giles Trent had recently disposed of.

'I used my common sense,' she said, and rubbed her hands together briskly. There was a trace of the Highlands in her voice.

The young doctor bade us all goodnight and departed. Goodness knows what Dicky had told him but, despite his little outburst, his manner was uncommonly respectful.

'And you're the man my brother works for,' said Miss Trent.

'Yes, I am,' said Dicky. 'You can imagine how shocked I was to hear what had happened.'

'Yes, I can imagine,' she said frostily. I wondered how much she guessed about her brother's work.

'But I wish you hadn't called in your local doctor,' said Dicky. He gave her the card listing the Departmental emergency numbers. 'Much better to use the private medical service that your brother is entitled to.' Dicky smiled at her, and held his smile despite the stern look she gave both to the card and to Dicky. 'We'll get your brother into a nice comfortable room with a night nurse and medical attention available on the spot.' Again the smile, and again no response. Miss Trent's countenance remained unchanged. 'You've done your bit, Miss Trent.'

'My brother will stay here,' she said.

'I've made all the arrangements now,' said Dicky. He was a match for her; Dicky had the thick-skinned determination of a rhino. I was interested to watch the confrontation, but again and again my thoughts went back to Fiona. Morbidly I visualized her with Bret: talking, dancing, laughing, loving.

'Did you not hear what I said?' Miss Trent asked calmly. 'My brother needs the rest. You'll not be disturbing him.'

'That's a decision that neither of us need concern ourselves with,' said Dicky. 'Your brother has signed a contract under the terms of which his employers are responsible for his medical care. In situations like this' – Dicky paused long enough to raise an eyebrow – 'your brother must be examined by one of our own medical staff. We have to think of the medical insurance people. They can be devils about anything irregular.'

'He's sleeping.' This represented a slight retrenchment.

'If his insurance was revoked, your brother would lose his pension, Miss Trent. Now I'm sure you wouldn't want to claim that your medical knowledge is better than that of the doctor who examined him.'

'I did not hear the doctor say he could be moved.'

'He wrote it out for me,' said Dicky. He'd put the piece of paper between the pages of his magazine and now he leafed through it. 'Yes, here we are.' He passed the handwritten document to her. She read it in silence and passed it back.