Have you ever looked at a film’s credits and wondered what the difference was between the “story” written by these guys over here and the “screenplay” written by those guys over there? Often, the “story” in question used to be a proper screenplay in its own right, until someone else was hired to give it a bit of a polish, and by the time the finished film came out, it became impossible to say for sure which bits were the work of which people.
You can see something of this process whenever an old movie is remade; some of the more confounding plot twists in, say, last year’s versions of The Stepford Wives and The Manchurian Candidate begin to make sense when you watch the original versions of those films and realize why and how the stories went in those directions. And when remakes go off in their own direction, it often says something revealing about the people that made them. But remakes are generally made many years after the originals — or, in the case of foreign-film adaptations like The Magnificent Seven, after a story has been transposed into a different culture — so the new films still tend to have an identity of their own.
So apart from the film’s actual content — more on that in a moment — the most remarkable thing about Dominion: Prequel to The Exorcist is that, in tandem with last year’s Exorcist: The Beginning, it provides a unique opportunity to see how tweaking a screenplay can produce a very different film, even when many of the same elements are in place.