“Yes, I did. And she solved my problem, or so I thought. Her plan was brilliant. Following her advice, I suggested to Richard only one deviation from his proposed plan. His idea was that once Harriet and Ida were dead, he would kill me and then himself. Naturally, as an authoritative man accustomed to being in charge of whatever mattered to him, he wanted to be the one in control until the end.

“Nancy told me I had to persuade Richard that I should kill him rather than have him kill me. ‘Impossible!’ I said. ‘He will never agree.’ But Nancy said that he would if I approached him in the right way. I had to pretend to be more committed to our goal than he was. She was right. It worked. I went to Richard and said that it was not enough for the four of us to die: me, him, Harriet and Ida. Nancy had to be punished too. I pretended that I would be happy to die only once she was dead. She was more evil than Harriet, I said. I related an elaborate tale of how Nancy had callously plotted to seduce Patrick away from his wife, and would not take no for an answer. I told Richard she had confessed to me that her true motive for speaking up at the King’s Head was not to help Patrick but to hurt Frances. She hoped that Frances would take her own life, or abandon Patrick at the very least and return to her father in Cambridge, leaving the way clear for Nancy.”

“More lies,” said Poirot.

“Yes, of course, more lies—but ones suggested to me by Nancy herself, and ones that did the trick! Richard agreed to die before me.”

“And he did not know that Samuel Kidd was involved, did he?” said Poirot.

“No. Nancy and I brought Sam into it. He was part of our plan. Neither of us wanted to climb out of that window and down the tree—we both feared we would fall and break our necks—and after locking the door from the inside and hiding the key behind the tile, that was the only way to leave Room 238. That’s why Sam was needed—that and the impersonation of Richard.”

“And the key had to be hidden behind the tile,” I muttered to myself, checking I had it all straight in my mind. “So that, when you came to tell us your story—the one we heard at Mr. Kidd’s house—it all appeared to fit: Richard Negus hid the key to make it look as if a murderer had taken it because he was involved in a plan to frame Nancy Ducane.”