In this spooky thriller, an evil sorcerer invites an innocent young man and his girl friend to his dark and scary mansion. The two have no idea that the black magician is planning to sacrifice the young man to atone for the evil misdeeds of his ancestors who 200 years ago burned the wizard's relative, a witch, at the stake. A crazy party precedes the gruesome ritual. Fortunately for the young couple the sage Professor March (80-year-old Boris Karloff in one of his final films) is also a skilled magic maker and is there to save them. The film is also titled Curse of the Crimson Altar and The Crimson Altar.