Noble-born brawler and debaucher, Denis de Beaulieu (Richard Stapley), is selected by the scheming Sire Alain de Maletroit (Charles Laughton) to be forced into marrying his only niece Blanche de Maletroit (Sally Forrest). Whilst carousing at an inn, Denis is tricked into a fight with one of Maletroit's men and ends up shooting him dead. Whilst fleeing from the chasing mob, Denis takes refuge by entering a strange door at the Maletroit manor, but soon finds himself in the midst of a nightmare from which he cannot escape. Forced to marry a woman he does not love, due to Sire de Maletroit's determination to wreak revenge on his family line, his every move is watched by the creeping manservant Voltan (Boris Karloff). Desperate to escape, the young couple decides to leave the house through the only exit known to them...the torture chamber.