Constantine(set in Los Angels) is a move loosely based off a graphic novel called Hellblazer, the differences of the characters are not dramatically altered, but altered to improve the concepts of these concepts of Characters, thus helping create a more understandable Initiating Incident. In the movie John Constantine is black-haired American, where as in the book he is blond and British, also the book version John was doomed to Hell for his his use of magic to attempt to murder his father. In the movie this is not so John is doomed for an unsuccessful suicide. The second act has differences to like in how John handles his business, in the book John does not like to fight, he refuses too, but instead he uses trickery, now Constantine in the movie fought with guns blazing, made it a whole lot more interesting. Then in the third act the character Gabriel is a villain in the film, but the book made it no fun with Gabriel as being more neutral, in the film Gabriel is a big part of the Climax of the movie. For the last interesting fact, the resolutions were altered also, you see in the movie John quits smoking cigarettes, and takes up the chewing gun habit, but in the book he quits then goes right back to smoking Weird message huh? The major similarities is mainly the major idea of the story, sending the Demons back to hell. These two versions of the story wouldn't be anywhere with out conflict, the whole roll of these versions is simply this; the blood of God, what killed his son Jesus, will give birth to the Son of the Devil. The Spear of Destiny is in the wrong hands and they must find out how save the world as we know it.