Classic Ealing comedy in which an embittered aristocrat sets out to murder the eight heirs that stand between him and succession to the family title. Louis Mazzini (Dennis Price) holds no love for the aristocratic family he counts as relations, the D'Ascoynes. The family cast his mother out when she decided to marry a 'commoner', Louis's father, and on her death refuse to allow her to be buried in the family vault. An outraged Louis vows revenge and begins working his way into the trust of the family to provide him with the opportunity to bump off the male heirs (all played by Alec Guinness) one by one. However, complications arise when he becomes romantically entangled with one of the widows of his victims, Edith D'Ascoyne (Valerie Hobson). Will Louis be able to stay the course and murder his way to a Dukedom?