Nightmare Castle (Italian: Amanti d’oltretomba) is a 1965 Italian horror film directed by Mario Caiano. The film stars Paul Muller, Helga Liné and Barbara Steele in a dual role. The film is set in a castle where Stephen Arrowsmith does experiments involving the regeneration of blood. After finding his wife with the gardener, he kills them both and uses their blood to rejuvenate his loyal assistant Solange. After this, Arrowsmith realizes his wife’s sister Jenny is actually inheriting the castle and marries her with the idea to drive her mad. Jenny meanwhile begins having nightmares where her sister tells her to murder Arrowsmith.
Mario Caiano shot the film in Rome and declared it his tribute to the Gothic genre and to actress Barbara Steele. Among reviews of the film, critics and historians note Steele’s dual performance.