Ulrich Mott is an eccentric and versatile social climber with grandiose plans to affect United States foreign policy. Encouraged in his attempts by his strategically chosen (and much older) wife, the well-connected journalist Elsa Brecht, Mott has a knack for making himself indispensable and impossible to ignore. The only one seemingly immune to his charms is Elsa’s daughter Amanda, who might simply disapprove of her mother marrying a much younger man – or perhaps she senses something more sinister beneath the smooth-talking surface?

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.

Set fifteen years after the original film, The Exorcist III centers around the philosophical Lieutenant William F. Kinderman who is investigating a baffling series of murders around Georgetown that all contain the hallmarks of The Gemini, a deceased serial killer. It eventually leads him to a catatonic patient in a psychiatric hospital who has recently started to speak, claiming he is the The Gemini and detailing the murders, but bears a striking resemblance to Father Damien Karras.