Spanish exploitation king Jésus "Jess" Franco helmed this gothic horror outing, as a very loose adaptation of Edgar Allan Poe's short story "The House of Usher." As it opens, Dr. Alan Harker (Antonio Mayans) receives a distressed letter from his former university professor-cum-mentor, Dr. Eric Usher (Howard Vernon), that prompts him to travel to Usher's castle. Once there, Dr. Harker discovers, to his utter horror, that Usher is trapped in the jaws of madness, obsessively attempting to resurrect his comatose daughter Melissa with the blood of abducted young girls. As death looms near, Usher enters a terrifying netherworld that finds him continually tormented by malevolent otherworldly forces including the spirit of his dead wife, that of his wayward housekeeper, and those of the many young women who have fallen prey to his abductions and homicides. As this occurs, Usher's castle itself begins to crumble in response to him, and Harker realizes that he must flee for his life.