The Exorcist

Blatty's novelization of a real case of possession that happened in a Washington Suburb (Mt. Ranier, MD) puts Regan, an adolescent girl, Living with her mother in Georgetown in Washington, into a more and more difficult situation. She exhibits strange symptoms, including levitation and great strength. When all medical possibilities are exhausted, her mother is sent to a priest who is also a psychiatrist. He becomes convinced that Regan is possessed and he and a second priest experienced in exorcism try to drive the spirit from Regan before she dies. Very graphic for its time. Source.

Definitly a must see movie. A classic.