A curse affects the Preston family, caused by their betrayal of the Satanic priest Jonathan Corbis (Ernest Borgnine). Corbis has harassed the Preston family for generations to obtain a Satanic book of great power. Corbis captures patriarch Steve Preston (George Sawaya), who is allowed to escape to warn his wife Emma (Ida Lupino) and younger son Mark (William Shatner) about Corbis' wrath. He tells them to give the book to Corbis, but during a rainstorm he melts into a waxy substance.