'It's not the end of the world, Tessa.'

'I've got no one to turn to,' she said between sobs. 'You're the only one I can talk to now that Fi has gone.'

'You have a thousand friends.'

'Name one.'

'Don't be silly. You have so many friends.'

'Is that your polite way of saying lovers, Bernard? Lovers are not friends. Not my sort of lovers anyway. The men in my life have never been friends. My love affairs have always been jokes… schoolgirl jokes. Silly pranks that no one took seriously. A squeeze, a hug, a couple of hours between the sheets in a very expensive hotel room. A weekend stay in the country house of odd people I hardly knew. Passionate embraces in ski chalets and quick cuddles in parked cars. All the flushed excitement of infatuation and then it's all over. We knew it couldn't last, didn't we? Goodbye, darling, and don't look back.'

'You always seemed so happy, Tessa.'

'I was, darling. Happy, confident Tessa, full of fun and always making jokes about my love life. But that was while I had George to go home to. Now I don't have George to go home to.'

'Do you mean…?'

'Don't look so alarmed, Bernard. I don't mean literally, darling. I don't mean that I'm moving in here with you. You should see your face.'

'I didn't mean that,' I said. 'If you leave George you can always use the boxroom. There's a bed there that we've used when my mother came to stay. It's not very comfortable.'

'Of course it's not comfortable, darling. It's a room made for mothers to stay in. It's a horrid, dark little room that would exactly suit a sister-in-law who came to stay, and who might otherwise stay too long.' She gave all her attention to the bubbles rising through the champagne and ran her fingertip down the glass to trace a line through the condensation.

'Sounds like you're determined to feel sorry for yourself.'

'But I am, darling. Why shouldn't I feel sorry for myself? My husband doesn't want me any more, and the only man I've always loved keeps looking at his lovely new watch and yawning.'

'Go back home and tell George you love him,' I said. 'You might find that everything will come out all right.'

'You must be Mrs Lonelyheart. I read your column every week.'

I picked the bottle out of the bucket and divided the last of the champagne between our two glasses. The bottle dripped icy water down my arm. She smiled. This time it was a more convincing smile. 'I've always adored you, Bernard. You know that, don't you?'

'We'll talk about that some other time, Tessa. Meanwhile do you think you can drive home, or shall I phone for a cab?'

'They don't have alcohol at the bridge club, that's the worst thing about it. No, I'm as sober as a judge. I will drive home and leave you in peace.'

'Talk to George. The two of you can sort it out.'

'You're a darling,' she said. I helped her into her smart suede car coat and she gave me a decorous kiss. 'You're the only one I can talk to.' She smiled. 'I'll be over here when nanny arrives. You get on with your work. No need to worry.'

'I'm flying to Berlin in the morning.'

'How wretched for you, Bernard. You won't be here to welcome the children.'

'No, I won't be here.'

'Don't worry. I'll go to Gloriette – opposite Harrods – and get them a superb chocolate cake with 'Love from Daddy' written on the top, and I'll tell them how sorry you are to be away.'

'Thanks, Tessa.'

I opened the front door for her but she didn't leave. She turned to me and said, 'I dreamed about Fiona the other night. I dreamed that she phoned me, and I said was she speaking from Russia, and she said never mind where she was speaking from. Do you ever dream about her, Bernard?'

'No,' I said.

'It was so vivid, my dream. She said I was to meet her at London Airport. I was to tell no one. She wanted me to bring her some photos.'

'Photos?'

'Photos of your children. It's so silly when you think of it. Fiona must have taken photos with her when she went. In this dream she desperately wanted these photos of the children. I dreamed she was shouting down the phone at me the way she did when we were children and she couldn't get her own way. Wake up, she shouted. It was such a silly dream but it upset me at the time. She wanted photos of you too.'

'What photos of me?'

'It was only a dream, darling. Oh, photos of you she left at my house a couple of months ago. She forgot to take them with her one night. Photos taken recently, for your passport, I should think. Awfully dull photos, I think, and portraits of the children. Isn't it odd how one dreams such silly trivial things?'

'Which terminal?'

'What do you mean?'

'In the dream. Which terminal at London Airport did she ask you to go to?*

'Terminal 2. Don't let it upset you, Bernard. I wouldn't have mentioned it if I'd known. Mind you, it upset me at the time. It was very early in the morning and I dreamed I answered the phone and the operator asked me if I'd accept a reverse-charge call from Bosham. I ask you, darling. From what deep dark confines of my brain-box did I dredge Bosham? I've never been there.' She laughed. 'George was awfully cross when I woke him up and told him. If the phone had really rung, I would have heard it, wouldn't I, he said. And then I realized it was all a dream. Mind you, the phone often rings without George hearing it, especially if he's been boozing at his club as he had that night.'

'I'd just try and forget about it,' I said. 'It's not unusual to get strange dreams after something like that happens.'

She nodded and I squeezed her arm. Her sister's betrayal had affected her deeply. For her, as for me, it was a personal betrayal that required a fundamental rethinking of their whole relationship. And that meant a fundamental rethinking of oneself. Perhaps she knew what was in my mind, for she looked up at me and smiled as if at some secret we shared.

'Forget it,' I said again. I didn't want Tessa to worry, and, on the practical level, I didn't want her to phone the telephone exchange and check if there really was a reverse-charge call from Bosham. It could only lead on to inquiries I was trying to avoid. I could follow Fiona's reasoning. By reversing the charges, she made sure the call didn't appear on the telephone bill of the house in Bosham and thus implicate her sister.

I kissed Tessa again and told her to look after herself. I didn't like the idea of Fiona wanting passport pictures of me. She didn't want them to go beside her bed.

I watched Tessa get into her silver VW. She lowered the car window so that she could blow me a kiss. The way the headlights flashed a couple of times, and the direction indicators winked, as she backed out of the tiny parking space, made me wonder if she was telling the truth about the availability of alcohol at her bridge club.

But when I went upstairs to bed I saw MacKenzie sprawled across the floor with his brains spattered over the wallpaper. It was some sort of hallucination. But just for a moment, as I switched on the bedroom light, his image was as clear and as real as anything I've ever seen. It was the shock and the drink and the tiredness and the anxiety. Poor little sod, I thought; I sent him to his death. If he'd been an experienced agent perhaps I'd not have felt so guilty about it, but MacKenzie was not much more than a child, and a novice at the spy game. I felt guilty, and as I prepared for bed I began to suffer the delayed reaction that my body had deferred and deferred. I shook uncontrollably. I didn't want to admit, even to myself, that I was frightened. But that image of MacKenzie kept blurring into an image of myself, and my guilt was turning into fear. For fear is so unwelcome that it comes only in disguise, and guilt is its favourite one.