This classic Ealing comedy returns to cinema screens in time for it's 70th birthday. 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', and on her death refused 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 romanically entangled with the widows of one of his victims, Edith (Valerie Hobson). Can he stay the course and murder his way to Dukedom?