Quick recap
Financier Rex Fortescue dies of poison at his office, his pocket full of rye. Soon after, his young widow, Adele, is poisoned at tea, and the maid, Gladys, is found strangled by the clothesline with a peg on her nose. Miss Marple, who trained Gladys, heads to the family home, Yewtree Lodge. She ties the deaths to the rhyme "Sing a Song of Sixpence" and to an old deal of Rex's, the Blackbird Mine. The rhyme was only cover. The killer is the son, Lance, just back from Africa, who used Gladys, in love with him, to plant the poison and then killed her. At the end, Marple gets a letter Gladys mailed before she died.
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