10 Most Twisted Asylum Horror Movies

While The Exorcist II: The Heretic was a major disappointment, William Peter Blatty's The Exorcist III is a cracking horror movie that works great as a standalone effort or as a sequel to The Exorcist.

Set 17 years after the events of the first movie - and completely ignoring The Exorcist II - George C. Scott's Lt. Kinderman has a slew of sinister, purportedly demonic murders on his hands. With these murders all falling in line with the habits of the infamous Gemini Killer (Brad Dourif), Kinderman has quite the mystery to solve - particularly as the Gemini Killer was executed 15 years ago.

Upon visiting a psychiatric unit for advice, Kinderman is introduced to an amnesia-suffering patient who was found 15 years ago and who claims to be the Gemini Killer. As it happens, this patient is none other than Father Karras of the first film; a possessed Karras whose appearance briefly changes to that of the Gemini Killer.

It's revealed how, after the events of The Exorcist, Karras had been taken over by the same entity that tormented young Regan MacNeil. Pissed off at being exorcised, this demon uses Karras' carcass as a conduit for the spirit of the Gemini Killer, with that spirit leaving Karras on a nightly basis to corrupt other patients and hospital staff to committing atrocities.