“He didn’t strike her with the pestle,” said Joanna. “There was a clock weight there too, with hair and blood on it. He pinched the pestle, they think, on the day Aimée was arrested, and hid the book pages in her house. And that brings me back to my original question. What about Aimée Griffith? The police actually saw her write that letter.”

“Yes, of course,” said Miss Marple. “She did write that letter.”

“But why?”

“Oh, my dear, surely you have realized that Miss Griffith had been in love with Symmington all her life?”

“Poor thing!” said Mrs. Dane Calthrop mechanically.

“They’d always been good friends, and I dare say she thought, after Mrs. Symmington’s death, that some day, perhaps—well—” Miss Marple coughed delicately. “And then the gossip began spreading about Elsie Holland and I expect that upset her badly. She thought of the girl as a designing minx worming her way into Symmington’s affections and quite unworthy of him. And so, I think, she succumbed to temptation. Why not add one more anonymous letter, and frighten the girl out of the place? It must have seemed quite safe to her and she took, as she thought, every precaution.”

“Well?” said Joanna. “Finish the story.”

“I should imagine,” said Miss Marple slowly, “that when Miss Holland showed that letter to Symmington he realized at once who had written it, and he saw a chance to finish the case once and for all, and make himself safe. Not very nice—no, not very nice, but he was frightened, you see. The police wouldn’t be satisfied until they’d got the anonymous letter writer. When he took the letter down to the police and he found they’d actually seen Aimée writing it, he felt he’d got a chance in a thousand of finishing the whole thing.

“He took the family to tea there that afternoon and as he came from the office with his attaché case, he could easily bring the tornout book pages to hide under the stairs and clinch the case. Hiding them under the stairs was a neat touch. It recalled the disposal of Agnes’s body, and, from the practical point of view, it was very easy for him. When he followed Aimée and the police, just a minute or two in the hall passing through would be enough.”

“All the same,” I said, “there’s one thing I can’t forgive you for, Miss Marple—roping in Megan.”

Miss Marple put down her crochet which she had resumed. She looked at me over her spectacles and her eyes were stern.

“My dear young man, something had to be done. There was no evidence against this very clever and unscrupulous man. I needed someone to help me, someone of high courage and good brains. I found the person I needed.”

“It was very dangerous for her.”