Lost Souls compares itself to The Exorcist, but that's only because it's also about demonic posession. There have been quite a few movies lately that deal with the Devil, and Lost Souls is, so far, the worst of the bunch.
Winona Ryder plays Maya, a woman who knows all about exorcisms, and has stumbled across the so-called fact that Satan is about to return to Earth by taking human form. Ben Chaplin plays Peter, the poor guy that's going to be Satan's chosen host, unless Maya can find a way to defeat the Prince of Darkness, and save the world from the ultimate Evil. I've given what I'm fairly certain this film's plot is, since, in the movie, it all makes about as much sense as a Pokemon cartoon.
This movie sets up a lot of parallel plotlines that never amount to anything, and it's entire climax relies on many things that defy logic. It also refers to events that apparently happen to characters in the story, but are not seen in the movie! For example, those last two sentences you just read are less vague than most of this movie is. Want a real example? One of the pivotal points in the film hinges on a car's digital dashboard clock being exactly accurate with the timing of Satan's return. Gimme a break!
What's worse is that Winona Ryder, an actress whose work I usually enjoy, seems as lost in this movie as anyone unfortunate enough to see it! She never really seems to get a handle on how her character is to behave, and her performance of Maya is different in every scene. There is no reason given for her ever-changing personality, other than perhaps Winona's own confusion over who her character is supposed to be. The audience is left wondering that, too!
This film was actually finished over a year ago, but wasn't released until now. No doubt it wanted to be associated with the release of the Director's Cut of The Exorcist. I'm only guessing, but I think this movie got edited to death. If not, then the screenwriter was an idiot. Either way, Lost Souls is a lost cause.