A letter for Miss Marple from a recently deceased friend promises a large reward for investigating a crime - without telling her who was involved, or when it happened! When she accepts, she is given a reservation for a coach tour of historic homes and gardens. She has fifteen fellow-passengers - and one of them knows a…

Marple is asked by her lawyer, Christian Gilbranson, to visit his step-mother, Carrie Louise Serrocold, an old friend of Miss Marple's, at her country estate. Carrie's husband, Lewis, confides to Miss Marple that he suspects someone is slowly poisoning his wife, and when Gilbranson visits the mansion, he is mysteriousl…