A sense of danger pervades the rambling Victorian mansion in which Jane Marple’s friend Carrie Louise lives. Used as a rehabilitation centre for delinquents, the building teems with dangerous inmates, one of whom attempts to shoot the administrator, Lewis Serrocold. Neither is injured. The same cannot be said of a mysterious visitor – shot dead simultaneously in another part of the building. Miss Marple must use all her cunning to solve the riddle of the stranger’s visit… and his murder.