The Fall of the House of Usher (1950)

A traveler arrives at the Usher mansion to visit his old friend, Roderick Usher. Upon arriving, however, he discovers that Roderick and his sister, Madeline, have been afflicted with a mysterious malady: Roderick's senses have become painfully acute, while Madeline has become nearly catatonic. That evening, Roderick tells his guest of an old Usher family curse: any time there has been more than one Usher child, all of the siblings have gone insane and died horrible deaths. As the days wear on, the effects of the curse reach their terrifying climax.