Vampyros Lesbos (1971)

In Istanbul, Linda Westinghouse, a lawyer at Simpson & Simpson, has erotic dreams about a mysterious woman each night. Her therapist, Dr. Alwin Seward, encourages her to find a new lover. Tasked with settling an inheritance dispute involving the Hungarian Countess Nadine Oskudar, who has inherited property from Count Dracula, Linda leaves her boyfriend Omar at the Istanbul Hilton and heads to Kadidados Island. While waiting for transportation, a local warns her that the island is a place of death and madness, but she dismisses his advice. Upon arriving, she meets Countess Oskudar, a lesbian vampire who becomes infatuated with Linda. After the Countess drinks Linda's blood, she suffers from amnesia and ends up in a mental institution. There, Dr. Steiner, a vampire expert, treats her and places an ad in the newspapers. Omar eventually finds Linda, and Dr. Steiner teaches her how to kill a vampire. Linda must find the strength to resist the Countess's allure and confront her to end the vampire's threat.