I love this film, something of an unsung classic. I cant recommend it highly enough.This was very original at the time and has heavily influenced such films a se7en and any other serial killer thrillers that have come after it. This is a Supernatural Serial killer/detective thriller and I think this has suffered from being associated with the original film in name, when in reality it is a completely different type of film and really only refers to characters from the Exorcist 1, there is no sign of Linda Blair or her mother, similar themes but a completely different story, This would have worked better as a stand alone film and not as part of the Exorcist franchise. It is based on the book Legion by William Peter Blatty and is also directed by him. If you have not seen this you really should.