MacMahon is an Englishwoman, disappointed in love and life, who lets charming stranger Rathbone and his family into her home. He proves to be up to no good. Rathbone begins doping the lady with drugs to keep her quiet, then blackmailing her. She is finally rescued and Rathbone is arrested.
The whole thing, though well acted, is completely unbelievable and rather tedious to watch. It was remade in 1951 with Ethel Barrymore and Maurice Evans.