Reunited for the first time since 1932's The Old Dark House, Charles Laughton and Boris Karloff star in the second-echelon Universal melodrama The Strange Door. Based on a Robert Louis Stevenson story, the film casts Laughton as unhinged French aristocrat Alan De Maletroit. Angered when his sweetheart jilts him in favor of his brother Edmond (Paul Cavanuagh), De Maletroit tosses Edmond in his castle dungeon, then years later forces Edmond's daughter Blanche (Sally Forrest) into a marriage of convenience with the seemingly worthless Dennis de Beaulieu (Richard Stapley). Imprisoned within the walls of the castle by the overbearing De Maletroit, Blanche and Dennis fall genuinely in love, then conspire with De Maletroit's long-suffering servant Voltan (Boris Karloff) to escape. But the villain's torture chamber is just large enough for the three would-be escapees ... While Strange Door permits Charles Laughton plenty of room to dole out ham in thick, juicy slices, poor Boris Karloff has nearly nothing to do, much to the disappointment of his fans.
by Hal Erickson synopsis