Lust for a Vampire (1971)

In 1830, forty years to the day since the last manifestation of their dreaded vampirism, the Karnstein heirs use the blood of an innocent to bring forth the evil that is the beautiful Mircalla - or as she was in 1710, Carmilla. The nearby Finishing School offers rich pickings not only in in the blood of nubile young ladies but also with the headmaster who is desperate to become Mircalla's disciple, and the equally besotted and even more foolish author Richard Lestrange.