One of the most profitable horror movies ever made, this tale of an exorcism is based loosely on actual events. When young Regan starts acting odd — levitating, speaking in tongues — her worried mother seeks medical help, only to hit a dead end. A local priest, however, thinks the girl may be seized by the devil. The priest makes a request to perform an exorcism, and the church sends in an expert to help with the difficult job.