Who removes the strange door from the chateau?
Sire Alain de Maletroit, plots revenge on his younger brother Edmond for stealing Alain's childhood sweetheart, who died giving birth to Edmond's daughter Blanche. Alain secretly imprisons Edmond in his dungeon for 20 years and convinces Blanche that her father is dead.
Alain intends to further debase Blanche as revenge against Edmond. Alain tricks a high-born drunken cad, Denis de Beaulieu, in to believeing he has murdered a man. Denis escapes a mob by entering the Maletroit chateau by an exterior door which has no latch on the inside. Alain makes Denis a captive intending to force the delicate Blanche into marriage with him.
Alain goes to the dungeon to torture Edmond with the news Blanche will be married to Denis, an unworthy rogue. After Alain leaves, Edmond asks the family servant Voltan to kill Denis before the wedding. However, Denis shows unanticipated redemptive qualities and he and Blanche fall in love. When Voltan comes to kill Denis, Blanche pleads with Voltan to spare his life and help him escape.
Their attempts to escape are foiled by Alain, who then seals Edmond, Blanche and Denis in a stone cell and starts a waterwheel that presses the cell walls inward to crush them to death. Voltan fights Alain and gets the key to the dungeon and pushes Alain into the waterwheel, temporarily stopping the crushing walls. Wounded by the guards, Voltan struggles to the dungeon and, with his dying breath, gets the key to Denis just as the walls start moving in again. Denis, Blanche and her father escape the cell. Denis and Blanche decide to stay together and Edmond has the strange door removed from the chateau.
Edmond