“Perhaps you would agree with Mrs. Ducane, Lord Wallace?” said Poirot. “You too are a painter, though of a very different kind. Ladies and gentlemen, St. John Wallace is a botanical artist. I saw his work in every room of his house when I visited—Lady Wallace was gracious enough to show me around, just as she was generous enough to provide a false alibi for Nancy Ducane. Lady Wallace, you see, is a good woman. She is the most dangerous kind of good: so far removed from evil that she does not notice it when it is right in front of her! Lady Wallace believed in Nancy Ducane’s innocence and provided an alibi to protect her. Ah, the lovely, talented Nancy, she is most convincing! She convinced St. John Wallace that she was eager to try her hand at his sort of painting. Lord Wallace is well connected and well known, therefore easily able to obtain what plants he needs for his work. Nancy Ducane asked him to obtain for her some cassava plants—from which the cyanide is made!”

“How the devil can you possibly know that?” St. John Wallace demanded.

“A lucky guess, monsieur. Nancy Ducane told you that she wanted these plants for the purpose of her art, did she not? And you believed her.” To the sea of open-mouthed faces, Poirot said, “The truth is that neither Lord nor Lady Wallace would ever believe a good friend of theirs capable of murder. It would reflect so badly upon them. Their social standing—imagine it! Even now, when everything I say fits perfectly with what they know to be true, St. John and Louisa Wallace tell themselves that he must be wrong, this opinionated detective from the Continent. Such is the perversity of the human mind, particularly where snobbish idées fixes are concerned!”

“Monsieur Poirot, I have not killed anyone,” said Nancy Ducane. “I know that you know I am telling the truth. Please make it clear to everybody gathered in this room that I am not a murderer.”

“I cannot do that, madame. Je suis désolé. You did not administer the poison yourself, but you conspired to end three lives.”

“Yes, but only to save another,” said Nancy earnestly. “I am guilty of nothing! Come, Jennie, let us tell him our story—the true story. Once he has heard it, he will have to concede that we did only what we had to do to save our own lives.”

The room was completely still. Everyone sat in silence. I did not think Jennie was going to move, but eventually, slowly, she rose to her feet. Clutching her bag in front of her with both hands, she walked across the room toward Nancy. “Our lives were not worth saving,” she said.