A preacher seeking to expose the truth behind a disturbed girl who may be inhabited by a demon confronts unthinkable horrors on a remote Louisiana farm in director Daniel Stamm's "The Last Exorcism," a shocking descent into the primeval fear of possession.

Tackling an exorcism tale in film is a tricky task following the exceptional success of William Friedkin's 1973 film "The Exorcist." It's a horror classic, and comparisons are inevitable. But "The Last Exorcism" smartly forges its own interpretation of a girl grappling with the disturbing notion that an otherworldly presence has decided to park itself in her body.

The film follows Reverend Cotton Marcus (Patrick Fabian) as he is called to examine young Nell Sweetzer (Ashley Bell), and purge her demon. He is a man drifting on autopilot, who playfully goes through the motions of preaching, and who is well versed in making money off the beliefs of disturbed religious fanatics. Consequently, his faith has waned over time.

At the request of Nell's father, played by Louis Herthum, Marcus travels to the family's Louisiana farm, bringing a documentary crew along to chronicle the event. The entire film is presented as their footage, which Marcus plans to use as a confessional for his less than savory exorcism practices.

However, when Nell's symptoms continue to point to an actual possession, Marcus is forced to embrace his faith again, and defuse a frantic father who sees his daughter's death as the only solution to save her.

What Worked

The film's first act quickly paints a rich picture of Marcus. He is a charismatic, fast-talking and often funny preacher, who despite some of his questionable practices, is immediately likable. Fabian is fantastic here.

"The Last Exorcism" takes its time to set up the premise, but it pays off. By the time the darker side of the story kicks in, you're invested in Marcus' story, thus the horrors of Nell's affliction receive added weight.

These horrors carry a refreshing emphasis on mood. This isn't a film propped up by gore. Stamm has helmed a picture where atmosphere and suggestion unite to create some truly uncomfortable and suspenseful moments. You can't say that about many of today's pictures, which reflects an unfortunate side of the genre. Studios should take notice.

Finally, Bell deserves credit for making many of the more frightening moments pay off. She has the right look of innocence and menace, which is so critical to compellingly sell the idea of possession. At one point, as she is perched menacingly on top of a dresser, you get a true sense that what is looking through her eyes is far from human.

And her disconcerting ability to contort her body -- no effect work used in the process -- provides the film its most iconic moment. Check out the movie poster for a hint.

What Didnt Work

Although the documentary format soundly added to some undeniably creepy moments, the film's finale lost some momentum from the format's limitations. Don't get me wrong, the finale reveals an intriguing surprise. But, by being restricted to one camera viewpoint during the climax's mayhem, you're left to wish for a clearer picture of this key moment in the story.

The camera at this point is so busy shaking and panning about in the chaos -- admittedly, for good reason -- that you can't fully absorb the terror of the moment. This consequently leaves the most unnerving moments confined to the film's second act.

Regardless, "The Last Exorcism" is still an engaging addition to the horror genre. And despite a PG-13 rating, it certainly ranks as one of the genre's best offerings in recent years.

Giving Credit Where Credit is Due

"The Last Exorcism" stars Patrick Fabian, Ashley Bell, Iris Bahr, Louis Herthum and Caleb Landry Jones. It was directed by Daniel Stamm ("A Necessary Death"), based on a script by "Mail Order Wife" writing duo Huck Botko and Andrew Gurland. "Hostel" helmer Eli Roth produced.

"The Last Exorcism" hits theaters Aug. 27.