“I used this sort of gloves at university for experiments in the lab,” she said. “Kloster’s fingerprints are on the page and it’s the only evidence I have against him. I don’t want them to get smudged with other fingerprints.”

I put on a pair of the gloves, with difficulty because they were too small, and swore to myself that it was the last favour she would get out of me. Once I had donned the gloves she slid the book towards me. It was an impressive volume, rather beautiful, with a tooled leather cover, gilded edges to the pages and a red ribbon as a marker.

“The night my parents died, when Bruno phoned, I remembered the Bible Kloster had returned to me at the conciliation meeting. After I’d hung up, before leaving for the hospital, I opened it at the page where the bookmark was. Kloster handed it to me as it is now, with the marker at this page.”

I opened the Bible at the marked page, near the beginning. It was the part in the Old Testament about the first murder-Abel’s death at the hands of his brother Cain-and Cain’s final plea, when God condemns him to exile. I read aloud, doubtfully, as I wasn’t sure it was the paragraph she meant:

Behold, thou hast driven me out this day from the face of the earth; and from thy face shall I be hid; and I shall be a fugitive and a vagabond in the earth; and it shall come to pass, that every one that findeth me shall slay me.

“A little further on: God’s promise to Cain.”

And the Lord said unto him, Therefore whosoever slayeth Cain, vengeance shall be taken on him sevenfold.

“Vengeance shall be taken on him sevenfold. Do you see? That was the line Kloster wanted me to read. The line intended for me. When I was working for him he dictated a novel that was never published, about a Cainite sect that took this notion of proportion literally in avenging their own. Divine law, as laid down for them by God, wasn’t an eye for an eye, a tooth for a tooth. It was seven for one.”

She had again fixed her gaze on me anxiously, watching my face for the slightest hint of scepticism. I handed back the Bible and removed the gloves.

“Seven for one. But it hasn’t been carried out exactly, has it?” I said. I realised I was beginning to feel truly afraid of her.

“My God, can’t you see? It’s taking place step by step. And if no one realises what’s happening, if no one stops him, he’ll just keep going.”

“But I still don’t understand,” I said, “how it could have been him in the first two cases you’ve told me about.”

“Yes, that was what was driving me most crazy. From the moment I opened the Bible and read that sentence I no longer had any doubt that it was him, but I still couldn’t see how he’d done it on either occasion. It was all I could think about. I even stopped eating during that time. I was in a kind of fever that prevented me from doing anything else. Actually I had an idea how he’d done it in my parents’ case. All he had to have done was follow me to the house that first summer and he’d have seen the little wood where we picked mushrooms. It was the only piece of information he didn’t have. I think he went back to Villa Gesell a couple of days before my parents’ wedding anniversary and scattered the poisonous fungi amongst the edible ones, but with the base missing, so there was no way of distinguishing between them. He removed the bases. And before leaving he made sure he left a few buried in leaf litter, in case there was a forensic examination afterwards.”

I tried to picture Kloster-the Kloster who appeared in the papers-engaged in such horticultural skulduggery.

“I suppose it’s possible, though it sounds a little complicated. It seems more like the kind of murder he’d devise for one of his novels,” I said. But at the same time, and perhaps precisely because of that, I had to admit to myself that it didn’t seem all that unreasonable. “But how could he have managed it with your boyfriend?”

Luciana looked at me, eyes shining, as if she were about to confide a magical formula that she alone in the world had discovered.

“‘The cup of coffee with milk. That was the key. I woke up with a start early one morning and it came to me: I remembered the row with Ramiro over the waitress and how my coffee-the one with milk-was always cold. I’d thought it was petty spitefulness on her part when in fact, with hindsight, I realised it was just something all waiters do: to save herself a trip she sometimes waited for another order to be put on her tray, together with ours. As she was the only one waiting on the tables outside, it also quite often happened that orders were left at the bar for a minute, until she went back inside. Kloster was sitting right there, where the owner of the bar placed the trays with the cups. And he knew very well that I always had milk in my coffee, which meant he knew that the black coffee had to be Ramiro’s. He simply waited for the first rough day, so that it would look like an accident.”

“Do you mean he poisoned your boyfriend’s coffee?”

“I don’t think it was poison; that would have been too risky. He must have known that there’d be a routine postmortem afterwards. I think he chose a substance that pathologists wouldn’t automatically be looking for, something that could cause arrhythmia, or the beginnings of suffocation, or maybe massive cramps. He was a swimmer, so he’d know, say, that a sudden potassium deficiency causes cramps. It could simply have been a powerful diuretic. At first, I didn’t realise exactly how it had all happened. I thought I’d have to convince Ramiro’s parents to have his body exhumed, but now I think that would only have made things worse. I’m sure he planned this too: nothing unusual would be detected and he’d be above suspicion once again.”

“Did you tell anyone about this?”

Her face darkened. “My brother. That morning, when it all suddenly became clear to me, I went to see him. He was working a shift at the hospital. I think I was a little overwrought: I hadn’t slept for several nights since the funeral. My hands were trembling and I was almost feverish with excitement. I showed Bruno the passage in the Bible and told him about my suing Kloster, and the death of Kloster’s daughter, the Cainites and sevenfold vengeance. I explained how I thought he’d planned the deaths. But I got a little muddled: I couldn’t explain it as clearly as I’d understood it. At a certain point I realised he was no longer listening, but was watching me with the eyes of a doctor. He looked genuinely alarmed. He saw that my hands were shaking and asked how long I’d gone without sleep. He told me to wait there and left the room for a moment. The book he’d been reading was lying on the desk. There was something horribly familiar about the cover so I turned it round: it was one of Kloster’s novels. I think at that moment I collapsed. My brother reappeared with a psychiatrist who was on duty, but I wouldn’t answer any of her questions. I knew what they were thinking. The psychiatrist said they’d give me something to help me sleep. She used a horrible patronising voice, as if she were explaining something to a child. My own brother gave me the injection. My own brother, who was reading one of Kloster’s novels during his shift.”

“If it was the novel that came out that year, I don’t find it too surprising: it was an even bigger hit than his previous one. It would have been hard to find someone who wasn’t reading it.”

“That’s just it. That’s why I was so devastated. I saw how perfect his plan was. It wasn’t surprising-it was quite natural-that everything should go his way. It’s what I said to you at the beginning: this was maybe the most cunning part. His name was everywhere, he’d become a public figure, moving in circles beyond the reach of mere mortals. So when I tried to point the finger at him everyone looked at me as my brother had, and rushed for psychiatrists.”

“But after you were given the tranquilliser…”