The Strange Door (1951)

Alain, the Sire de Maletroit (Laughton), plots revenge on his younger brother Edmund (Cavanagh) for stealing Alain's childhood sweetheart, now deceased. Alain imprisons Edmund in a dungeon for 20 years. He then convinces Edmund's grown daughter Blanche (Forrest) that her father is dead. As Blanche's mother (Alain's lost love) died in childbirth, Maletroit intends to further antagonize Blanche by reducing her life to a miserable hell. As the film begins, he tricks a high-born drunken cad, Denis de Beaulieu (Richard Stapley), to pass through the sole, exterior door of the Maletroit chateau, which has no latch handle on the inside, making him a captive, with the intent of forcing the delicate Blanche into marriage with him. However, Denis has unanticipated redemptive qualities, and he and Blanche fall in love. Their attempt to escape is initially foiled by Alain, who seals Edmund, Blanche and Denis in a stone deathtrap designed to crush the lot of them. Maletroit's disloyal manservant Voltan (Karloff) comes to their aid and dies effecting the escape of Denis, Blanche and her father from a dungeon cell, the walls of which are crushing in on them under pressure of river water churned against them by a water wheel on the chateau. Alain dies when he falls into the river and is caught up in the water wheel, his fat body jamming it to a halt.