From the moment she arrives in Freiberg, Germany, to attend the prestigious Tans Academy, American ballet-dancer Suzy Bannion senses that something horribly evil lurks within the walls of the age-old institution.

12-year-old Regan MacNeil begins to adapt an explicit new personality as strange events befall the local area of Georgetown. Her mother becomes torn between science and superstition in a desperate bid to save her daughter, and ultimately turns to her last hope: Father Damien Karras, a troubled priest who is struggling with his own faith.