The Fall of the House of Usher.

After a long journey, a traveller and his wife arrive at the Usher mansion. Upon arriving, however, they discover that the mansion's sibling inhabitants, Roderick and Madeline Usher, 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 guests 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.