She smiled with relief. “It means a great deal to me that I’m not completely alone, Robin. It means I’m not the victim of my own delusions after all. Unless we both are.”

“She wouldn’t have wanted you to brood like this. To suffer on her account.”

“I know.”

“She’d have wanted you to be happy. Wouldn’t she?”

“Oh yes.”

“Then can’t you be? For her?”

“But I am. Sometimes. Don’t you see? What I’ve lost isn’t happiness. It’s balance. Equilibrium.” Suddenly, her expression crumpled into tearfulness. She tensed, as if to suppress a sob, released my hand, set the mug down and sighed. “They never tell you that about suicide. The thought of it… can be so exhilarating. So tempting.” She shook her head. “But I’m over it now. There’s nothing in the least bit tempting about a stomach pump. Take my word for it.” At that she smiled. And so did I. “Let’s go for a walk, Robin. I haven’t been out since they released me from hospital. We can leave a note for Sarah.”

We walked out onto Observatory Hill, then circled back to the suspension bridge. She meant to cross it, I knew. To tease me with the classic suicide’s view of the gorge. To test whether I’d try to stop her. But if I did, some slender thread of trust would snap between us. So I let her walk ahead, running her fingers along the railing as she went, squinting up at the high curving cables, or down at the grey winding snake of the river. She stopped in the centre and I caught her up. To find her eyes wide with joy.

“It’s good to be alive,” she said, turning towards me. “Isn’t it?”

I nodded. “Yes. It is.”

“I thought so even on Monday. It’s just… for a moment… for an hour at most… death… or oblivion… seemed even more attractive.”

“But not any more?”

“No. The world’s too wonderful to give up. I haven’t had my fill of it yet.”

“You never will.”

“I hope not. Except… do you think Mummy might simply have… had enough of the world?”

“I’d say the exact reverse.”

“I’m sure you’re right. It’s funny, though. When I saw her… in that place… the mortuary… she looked so… very very beautiful.”

“She was beautiful when she was alive.”

“But even more so when she was dead. Her skin was so pale. Like… flawless alabaster. And so cold. When I touched her, she opened her eyes, you know.”

“What?”

“Oh, it was an hallucination, of course. A figment of my over-stressed imagination. But it seemed so real. And the oddest thing was… how happy she looked.” Rowena took a deep breath, then started back towards the Clifton side of the bridge. As I fell in beside her, she said: “One of the things I used to like about mathematics was the certainty. An answer was either right or wrong. And if it was right, it was absolutely right and always would be. First principles governed everything. Two plus two equalled four and could never equal anything else.”

“Surely that’s still the case.”

“In mathematics, perhaps. But not in life. The variables are too great. It would be possible to rerun the events of the seventeenth of July last year a hundred times within the same parameters and produce a hundred different results. Many of them would be similar, of course. But none would be identical. Not exactly. Some would be dramatically different. Almost unrecognizable. A lot of times-maybe a majority of times-Mummy wouldn’t die. Wouldn’t even be in danger. Just because of some tiny scarcely noticeable variation. Like what she said to me. Or to you. And what we said in reply.”

“But we can’t rerun those events. Any more than we can-or should-take responsibility for the fatal variation.”

“I know.” She looked round at me and smiled. “That’s why I’m going to stop trying to.”

Rowena stayed behind when Sarah drove me to the station early that evening. Sarah, indeed, encouraged her to on the grounds that she should take her convalescence seriously. She was so emphatic on the point, however, that I suspected another reason was at work: an eagerness to compare notes with me on her sister’s state of mind. And so it turned out. No sooner had we left Clifton than she proposed we stop on the way for a drink. There were plenty of later trains than the one I’d been aiming for, so I was happy to agree.

A hotel bar supplied the privacy Sarah was seeking. She insisted on buying the drinks, as if I merited some reward for coming so far. Perhaps my willing response to her call had struck her as unusually-even oddly-generous. She wasn’t to know how helpless I was to resist any summons emanating from her family. I couldn’t have begun to explain why I should be. But I was. What she might regard as altruism was in reality a compulsion.

“I think seeing you’s done Rowena some good. She seemed much more relaxed this afternoon.”

“I didn’t do very much. Apart from listen.”

“Perhaps not. But she thinks you’re the only one who can understand what she experienced the day Mummy died.”

“I can try to. Though I don’t share her belief that your mother somehow foresaw her death.”

“No. Well, obviously she didn’t.”

“Nevertheless, her parting words to Rowena were… a little strange, weren’t they?”

“Ah. She told you them, did she?” Sarah toyed with her glass, rattling the ice cubes against each other and frowning, as if considering a complex legal question. “I do wish she’d forget what Mummy said and what it might have meant.”

“Why?”

“Because I’m running out of ways to avoid explaining to her that there’s a much more plausible interpretation than her fanciful ideas of precognition.”

Now it was my turn to frown. “Meaning?”

“Oh, come on. Mummy had lost her wedding ring. She’d brought a suitcase full of clothes back from Biarritz, but she didn’t leave it at home. It went with her in the car, on the grounds that she had no time to unpack.”

“I still don’t-”

“She was leaving Daddy. That’s what I think, anyway. It’s probably what she told him in the note he threw away. And it’s probably what she meant to tell Rowena. Until she thought better of it. Thank God.”

I wanted to contradict her. I wanted to deny that the mystery and ambiguity surrounding her mother’s death could be reduced to a simple act of marital desertion. But I was aware before I spoke that my protests would seem inexplicable. Why should I care whether it was true or not? Why should it be any of my business? In the end, I said nothing.

“I can’t be certain, of course. It’s not something I was expecting. Or had any reason to expect. But Mummy would have been quite capable of putting up a convincing front. Even Daddy might not have known she was planning to leave him. I can’t exactly ask him, can I? I’d have to accuse him of lying about the note-and of destroying material evidence.”

She’d thought this all along. Since before we’d met in Brussels. It was safe to tell me now, of course. The trial was out of the way. My testimony could no longer be tarnished by doubts about her mother’s image of impeccable virtue. Disgust at her father’s marriage to my sister-in-law must also have played its part. She probably took some small pleasure in enlightening me. Saw it as a vicarious slap in the face for Bella.

“Hadn’t it occurred to you, Robin? I mean, just as a theoretical possibility?”

“No. It hadn’t.”

“I was so worried it must have. And that you’d say so to Rowena. She mustn’t be allowed to think of it. It would be disastrous. She sees Mummy as perfect in every way.”

“But you don’t?”

“She was human. Like the rest of us. And she kept a great deal to herself. If she’d had enough of her marriage, it would be just like her to conceal the fact from Rowena and me. And to endure it until we were no longer dependent on her. Well, I was already off her hands. And Rowena was about to follow. Maybe last year seemed the obvious time to make the break.”