Wealthy businessman Rex Fortescue collapses and dies in his office. It is determined that he was poisoned, and a handful of rye is found in his pockets. No one seems too upset, as everyone agrees that Rex was a tyrant. Soon, however, Rex's young wife also ends up poisoned. The maid, Gladys, whom Miss Marple trained, writes to her asking for help. Miss Marple arrives too late, as Gladys' body is found strangled. Miss Marple senses a connection between the deaths and a well-known nursery rhyme, Sing a Song of Sixpence. Now it is up to her to find the cold-blooded killer and to deliver justice.