Dr. Mandeville (Christopher Lee) and his sister Sarah (Joan Collins) try to locate two suitcases of money hidden on the large estate of one of his former patients but their plans are thwarted when mentally unstable Andrew (Robert Hardy) arrives to claim the estate which had been left to him by the owner before he died. Andrew soon begins to have flashbacks to the murders committed by the previous owner Edward (Hardy as well). As the story unfolds it sheds light on the events of 30 years or so before when Edward had planned to leave his wife Victoria (Jean Marsh) for the younger and more attractive governess of their two children. In desperaration Victoria had encouraged the two children to murder the governess whilst she attempted to seduce Edward in the bedroom. In a fit of rage Edward strangled his wife and killed the children with a sword before bricking all four corpses up behind a wall with the two cases of money.