I was scrolling through Facebook and found an article titled, "The Exorcist's Unofficial Sequel is definitely worth your time." Clickbaity? You bet. Did I click on it? Damn straight! I'm a sucker for most things The Exorcist. Now, I've never seen the movie The Exorcist II: The Heretic, or something like that nor have I seen the new movie. I have read and watched the Exorcist and Legion (The Exorcist III) and saw the first season of the short lived Exorcist series. I also so one of the shitty prequels that takes place in Africa.
So it turns out it is about William Peter Blatty's movie The Ninth Configuration. Apparently he reworked an earlier novel of his, Twinkle Twinkle "Killer" Kane, and made it the second of what he himself calls his, "Spiritual Trilogy," made up of The Exorcist, The Ninth Configuration and the Exorcist III.
The best way to describe the movie is Shutter Island well before Shutter Island, except with a bigger emphasis on faith. I'm convinced Blatty became a horror Icon by accident. What I mean is, The Exorcist is definitely a horror book and movie, but Legion, the book, wasn't scary. Much more in line with this movie, characters exploring their inner faith and struggles when faced with external horrors which are all too real. In the case of Legion, we follow detective Kinnerman (sp?) from the first book/movie as he explores the ideas of Heaven, Hell, angels and demons in the face of horrific murders. In The Ninth Configuration we have a psychiatrist being challenged by his patients who are Vietnam War vets suffering from all sorts of mental disorders due to the war.
It's a very.... 70s film. Kinda like the original Westworld movie. Short, to the point with some odd shots. Jason Miller comes back as one of the loonies which means he is in all three of Blatty's movies. It was interesting, but can't say I recommend it unless you're into that kind of discourse. Might look for the book if it's still in print, if not I'll have to scour the second hand stores.