“But at once I came up, as I told you, against impossibility. Patrick Redfern could not have killed her since he was on the beach and in Miss Brewster’s company until the actual discovery of the body. So I looked about for other solutions—and there were several. She could have been killed by her husband—with Miss Darnley’s connivance. (They too had both lied as to one point which looked suspicious.) She could have been killed as a result of her having stumbled on the secret of the dope smuggling. She could have been killed, as I said, by a religious maniac, and she could have been killed by her stepdaughter. The latter seemed to me at one time to be the real solution. Linda’s manner in her very first interview with the police was significant. An interview that I had with her later assured me of one point. Linda considered herself guilty.”

“You mean she imagined that she had actually killed Arlena?”

Rosamund’s voice was incredulous.

Hercule Poirot nodded.

“Yes. Remember—she is really little more than a child. She read that book on witchcraft and she half-believed it. She hated Arlena. She deliberately made the wax doll, cast her spell, pierced it to the heart, melted it away—and that very day Arlena dies. Older and wiser people than Linda have believed fervently in magic. Naturally, she believed that it was all true—that by using magic she had killed her stepmother.”

Rosamund cried:

“Oh, poor child, poor child. And I thought—I imagined—something quite different—that she knew something which would—”

Rosamund stopped. Poirot said:

“I know what it was you thought. Actually your manner frightened Linda still further. She believed that her action had really brought about Arlena’s death and that you knew it. Christine Redfern worked on her too, introducing the idea of the sleeping tablets to her mind, showing her the way to a speedy and painless expiation of her crime. You see, once Captain Marshall was proved to have an alibi, it was vital for a new suspect to be found. Neither she nor her husband knew about the dope smuggling. They fixed on Linda to be the scapegoat.”

Rosamund said:

“What a devil!”

Poirot nodded.