Wealthy mogul Rex Forsythe dies at work of poisoning from an obscure toxin found in the berries of the yew tree. There’s some grain in his coat pocket, which turns out to be rye. The Scotland Yard detective is intrigued by this.
Rex had two sons and a daughter, and a younger second wife (don’t they all?), all of whom would benefit from his death. He was also kind of a jerk that no one would really miss. Also in the Forsythe house (Yewtree Lodge) is his last first wife’s sister, Effie, and a few servants, including Gladys Martin, who used to work for Miss Marple years ago. Then, within a day or so of his death, Rex’s wife and Gladys are both also murdered. The wife is killed by cyanide in her tea (whilst eating bread and honey). Gladys is found in the yard near some hanging laundry (get it?).
Miss Marple reads about the murders in the newspaper and heads for Yewtree Lodge. Gladys was an orphan, she really had no one, except for Miss Marple. The Inspector realizes that Miss Marple can be of help to him – he recognizes talent when he sees it. Miss Marple has caught on to the pattern here, and has the police ask about blackbirds. But – are the crimes really following the nursery rhyme, or is the tail wagging the dog?
Miss Marple does her usual poking around, and thinks her way through the problem, all the while putting on her scatty, fluffy old bird act. It works for her, as ever, but only so far. She and the inspector figured out who did it, but they may not be able to prove it. But maybe a letter from the late Gladys may have something they need? Hmmmm.