Nightmare Castle

Nightmare Castle Italian Amanti doltretomba is a 1965 Italian horror film directed by Mario Caiano. The film stars Paul Muller, Helga Lin 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 wifes 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.

Stephen Arrowsmith Paul Muller, a scientist studying the regeneration of blood through application of electricity, has his home and laboratory in the castle owned by his wife Muriel Barbara Steele. Arrowsmith finds her having sex with a gardener, David. He disfigures David with a hot poker and burns Muriels face with acid before electrocuting both of them. Arrowsmith removes their hearts and hides them in an urn. He uses their blood to rejuvenate the aged servant, Solange Helga Lin.Later, Arrowsmith is told that he is not Muriels heir, but that the estate has been willed to her sister, Jenny Barbara Steele, who is mentally unstable. Arrowsmith marries her, planning to have Solange drive her insane. Jenny begins having nightmares, which include the sound of beating hearts and Muriels voice urging her to murder Stephen. Arrowsmith brings Jenny to Doctor Derek Joyce Marino Mas, who becomes convinced that supernatural forces are at work. Joyce discovers the hidden hearts of Muriel and David. The murdered dead return as ghosts. Muriel burns Stephen alive while David reduces Solange to a skeleton by draining her blood. Joyce and Jenny leave the castle and burn the disembodied hearts. ........

Source: Wikipedia