Context: Six weeks after the death of her mother, Nancy Perkins' father (Thomas B. Henry) marries Doris (Jeanne Dean), and decides to enroll the eighteen-year-old Nancy (Sandra Harrison) into a boarding school, the Sherwood School for Girls. They are greeted by the principal, Mrs. Thorndyke (Mary Adams), who emphasizes to Nancy that the school is not a corrective institution but a private preparatory school with a very good reputation. Nancy is immediately harassed by her dormmates that night, and at breakfast the next morning, after Thorndyke officially introduces Nancy to the girls, Myra (Gail Ganley), their leader, tells Nancy that it was good thing that she did not mention anything about the way they acted the previous night. Myra also tells Nancy about their secret club, "The Birds of Paradise," and introduces her to Eddie (Don Devlin), a young groundsman whom the "Birds" take turns dating. Myra is the assistant for Miss Branding (Louise Lewis), the school's chemistry teacher, who is writing a thesis about her belief that there is a "terrible power," "strong enough to destroy the world buried within each of us." If she can prove this is the case, she hopes that the scientific community will abandon their experiments with nuclear power and other weapons mass destruction. When Branding tells Myra that she is looking for a special girl on whom to experiment, Myra suggests Nancy. During chemistry class, Myra and her friend Nola (Heather Ames) deliberately switch a chemical in order to burn Nancy, causing her to react violently. Intrigued, Branding later talks with Nancy and gains her confidence. She then asks Nancy if she may hypnotize her and Nancy agrees. Branding places an amulet from antiquity around her neck, telling Nancy that it came from the Carpathian Mountain region and is capable of healing, as well as destroying and has the ability to release frightening powers. As Nancy gazes at the amulet, Branding hypnotizes her and instructs her to always obey her. Later, Eddie and two local boys, Tab (Jerry Blaine) and Joe (Jimmy Hayes), climb up into the girls' room as they are having Nancy's initiation party. In a nearby building, Branding hears the noise and, despite the distance, is able to re-hypnotize Nancy, turning her into a vampire. The party is broken up by the disciplinarian Miss Rivers (Edna Holland), who then sends Nola to the basement to fetch supplies. While in the basement, Nola is attacked by something subhuman and killed. The next morning, as police detective sergeant Stewart investigates the killing, Nancy is unable to wake up until Branding orders her and, when she relates a nightmare she had, Branding orders her to forget it. At police headquarters, the coroner informs Lt. Dunlap (Malcolm Atterbury) that he found two puncture wounds in Nola's jugular vein and that the body was drained of blood. A young assistant to the coroner, Mike (Paul Maxwell) who shared a room in med school with "an exchange student from a small town in the Carpathian Mountains," remembers his friend's stories about vampires. Dunlap is unimpressed in the theory. The girls later organize a Halloween scavenger hunt in the local cemetery, and Nancy is again transformed into a vampire and kills another girl, as well as Tab. The police subject all the girls in the scavenger hunt to a lie-detector test, however, Branding is able to alter Nancy's responses to the questions by remote hypnosis. Back at the school, Nancy, confused and frightened by her transformations, begs for Branding's help, but Branding assures her that the experiment will soon be over and that she will be proud of her part in saving mankind from self-destruction. The state threatens to close the school over the unsolved murders, and consequently, Thorndyke asks Branding to take over some of her duties while she attempts to calm concerned parents. Nancy's boyfriend from back home, Glenn, suddenly arrives at the school, alarmed at the news stories of the slaughters but Nancy acts cold toward him afraid 
 Question: How old is Nancy Perkins?
Output: eighteen year old