Jess Franco's Marquise De Sadeuncut (DVD)

A lonely aristocrat Miss Gray possesses vampire like qualities and lives alone when new reporter comes to do a story on her. It appears Doriana needs to suck the life out of men and women in a sexual way, in-order to stay young. However, she gets no sexual feelings or pleasure out of it. Those 'feelings' go to her TWIN sister who is locked up in an asylum.