A group of friends are meeting at the house of Miss Marple in St Mary Mead. As well as the old lady herself, there is her nephew – the writer Raymond West – the artist Joyce Lemprière, Sir Henry Clithering (a former Scotland Yard commissioner), a clergyman called Dr Pender, and Mr Petherick, a solicitor. As the conversation turns to unsolved mysteries; Raymond, Joyce, Pender, and Petherick all claim that their professions are ideal for solving crimes. So they form a club; every Tuesday night, a member of the group must tell of a real mystery, and the others will attempt to solve it.