Novelist based his best-seller on the last known Catholic-sanctioned exorcism in the United States. Transformed the little boy in the 1949 incident into a little girl named Regan, played by 14-year-old. Suddenly prone to fits and bizarre behavior, Regan proves quite a handful for her actress-mother, Chris MacNeil (played by, although reportedly based the character on his next-door neighbor ). When Regan gets completely out of hand, Chris calls in young priest Father Karras (), who becomes convinced that the girl is possessed by the Devil and that they must call in an exorcist: namely, Father Merrin (). His foe proves to be no run-of-the-mill demon, and both the priest and the girl suffer numerous horrors during their struggles. Received a theatrical rerelease in 2000, in a special edition that added 11 minutes of footage trimmed from the film's original release and digitally enhanced 's Oscar-winning sound work.