Thanks to the massive success of Paranormal Activity, the mockumentary format is experiencing a resurgence among horror movies, and the latest example is The Last Exorcism, which starts off with an intriguing concept only to lose momentum and coherence as it gets into its actual horrific elements. A disillusioned preacher (Fabian) decides to take along a film crew to document the fakery he uses to perform an exorcism, to expose it for the sham it is. Of course, the one case he uses to debunk the practice is the one that turns out to be a genuine demonic possession. Fabian is charismatic as the preacher, and Ashley Bell is suitably creepy as his subject, but the movie takes a long time to get going and then doesn’t know how to integrate its sillier supernatural elements into the realistic format. By the time the end rolls around, the good ideas have petered out.