The Exorcist III (1990)

The Exorcist III is a 1990 American supernatural horror film written and dircted by William Peter Blatty It is the third installment of The Exorcist series and a film adaptation of Blatty's novel Legion (1983) The film stars George C. Scott Ed Flanders Jason Miller Scott Wilson and Brad Dourif

Plot
Lieutenant William F. Kinderman (George C. Scott) investigates the murder of a 12-year-old boy named Thomas Kintry. Kinderman later takes his friend Father Dyer (Ed Flanders) out to see It's a Wonderful Life. Kinderman is informed of a second murder – a priest who was decapitated. Dyer is subsequently hospitalized and found murdered in his room the following day, with the misspelled words "IT'S A WONDERFULL LIFE", written on the wall in his blood.

The fingerprints at the crime scenes do not match, indicating a different person was responsible for each. Kinderman reveals to the hospital staff that the murders fit the modus operandi of serial killer James "The Gemini" Venamun (Brad Dourif), who was executed seventeen years prior.

Kinderman visits the head of the psychiatric ward, Dr. Temple (Scott Wilson), who relates the history of one of his patients. The patient was found wandering aimlessly seventeen years ago with amnesia. He was locked up, catatonic until he became violent and claimed to be the Gemini Killer. Kinderman sees that the patient is his old friend Father Damien Karras (Jason Miller). Karras' form appears to briefly change into that of the Gemini Killer. He expresses ignorance of Father Karras but boasts of killing Father Dyer.

That night, a nurse is murdered and Dr. Temple commits suicide. Kinderman returns to see Karras, who once again changes into the Gemini Killer. The Gemini Killer explains that he is being aided by a "Master" – the same entity who had previously possessed Regan MacNeil. The "Master" was furious at being exorcised by Karras, and is exacting its revenge by using Karras' body as a conduit for the Gemini Killer to continue his killing spree. Each evening, the soul of the Gemini leaves the body of Karras and possesses the other patients elsewhere in the hospital, using them to commit the murders. The Gemini Killer also reveals he had forced Dr. Temple to bring Kinderman to him.

The Gemini possesses an old woman and attempts to murder Kinderman and his family at their home, but the attack abruptly ends when Father Paul Morning (Nicol Williamson) arrives at the hospital and begins to perform an exorcism on Karras. The "Master" intervenes, taking over Karras' body, and Morning is severely wounded and mutilated. Kinderman rushes back to the hospital and, after finding Morning's body, attempts to euthanize Karras. The possessed Karras then torments and attempts to kill Kinderman. Father Morning manages to regain consciousness and tells Karras to fight. Karras briefly regains control of his body, but Kinderman shoots, killing Karras and freeing him from the Gemini.

Later, Kinderman watches on as Karras' body is buried.

Cast

 * George C. Scott as Lt. William F. Kinderman
 * Ed Flanders as Father Dyer
 * Nicol Williamson as Father Morning
 * Jason Miller as Patient X/ Damien Karras
 * Brad Dourif as James Venamun/The "Gemini Killer"
 * Scott Wilson as Dr. Temple
 * Grand L. Bush as Sgt. Atkins
 * Nancy Fish as Nurse Allerton
 * Tracy Thorne as Nurse Amy Keating
 * Barbara Baxley as Shirley