A poor man's The Exorcist grafted to a by-the-numbers police procedural, Scott Derrickson's Deliver Us from Evil gets more mileage from its hybrid premise than one would expect, by it quickly goes adrift in before coming to rest with an anti-climactic thud of a conclusion.
The story is based on the book Beware the Night by the real-life Sarchie and Lisa Collier Cool, which in turn purports to be based on actual events, and it opens with a vague prologue set a few years ago in Iraq, during which a trio of soldiers run afoul of, well, something.
The story jumps ahead to present day Brooklyn, where NYPD Sgt. Ralph Sarchie (Eric Bana) and his partner Butler (Joel McHale) investigate the bizarre case of a woman who attempted to feed her toddler to lions at the zoo, and quickly find themselves knee-deep in weirdness involving those three soldiers, demon possession, jump scares, a great deal of brooding, and not much else. When Sarchie, a lapsed Catholic, finally accepts that he's out of his depth, he joins forces with unconventional priest/professional exorcist Mendoza (Edgar Ramirez), and the two share inner demons in between hunting actual demons.
Derrickson, recently tapped to direct the forthcoming Dr. Strange movie for Marvel Studios, tread similar territory with the slightly better but just as anemic The Exorcism of Emily Rose. Here, he does a fine job of drenching the movie in an atmosphere of dread and foreboding, but it pulls his punches by inserting too much cheap humor (mostly from McHale, nicely cast against type as an adrenaline-junkie cop) and cheaper scares.
While the violence and gore are usually over-used in this type of fare, it's surprisingly under-utilized here, and the climactic exorcism scene is literally nothing but sound and fury. Visually, the interiors are veiled in shadow and the exteriors in grey overcast skies that are initially effective but quickly grow monotonous. Some counter-intuitive splashes of color here and there would have helped.
It's mostly during the movie's more introspective scenes that it becomes interesting. Sarchie's "it sucks being married to a cop" home life is rote, but his obligatory Deep Dark Secret is intriguing, as is Mendoza's backstory. Sadly, Sarchie's epiphany is underplayed, and under-exploited by demon and director alike.