A hit man isn't precisely the sort of role that Matthew McConaughey is known for, but in Killer Joe, he handles it so well that it's hard to imagine anyone else fitting the part. The character almost seems like some dark essence exorcised from deep within the shirtless, charming, vaguely sleazy McConaughey persona of the perennial rom-com—a subtext that's been lurking below the surface all along.
Calling Joe a crooked cop is an understatement, considering that he moonlights as a murderer, and though his straitlaced appearance and polished manners smack of Southern gentility, as the film progresses, we realize that he does make the occasional significant breach of etiquette. In the hands of McConaughey, Joe's presence is undeniably large and arresting. His appearance is manicured, he has a patient, sinister gait, and his emotions are virtually changeless. The character is a bit like a chromium-glazed Frank Booth—just as sadistic and volatile, but more pointed, focused, and calm.
In Killer Joe, a squirrelly, debt-ridden Texan named Chris (Emile Hirsch) decides to put a hit on his mother in the hopes that her life insurance will secure his financial freedom. Lured by the prospect of easy money, the man's oafish, emasculated father (Thomas Haden Church) conspires with him to hire a killer. And as the murderous gears are set in motion, we realize it's only a matter of time before things start to unravel.
Though this is a classic film-noir setup, director William Friedkin is not interested, as the Coen brothers were with Blood Simple, in writing a simple Texas noir. When Killer Joe arrives on the scene, he commandeers the plot away from this known arc, guiding it into very different territory. The chronically incompetent Chris, unable to pay Joe's fee up front, strikes a somewhat unorthodox deal with Joe: Chris's young sister, Dottie (Juno Temple), will be kept as a retainer until the debt is settled.
As Joe's relationship with the underage Dottie progresses and he becomes further entrenched within the family, Chris's rising frustration at his own inability to extract Joe from the household precipitates a power struggle that drives the remainder of the film. Details of the plot are best experienced firsthand, but as the mounting absurdity of the situation begins to wrest control of the film, the tone becomes increasingly unclassifiable. Darkly comic moments and outright sight gags intermingle with scenes of complete depravity and violence. Friedkin, of the classic thrillers The Exorcist and The French Connection, never allows the tension to fully break. As with a campy exploitation film, he's constantly treading a line of believability, keeping the audience uncomfortable with their own laughter.
The Southern Gothic style is heightened to the point of parody as the family sits down to dinner among the wreckage of their lives, bloodied and mangled from various altercations, and the film ends on a delightfully ridiculous crescendo that subverts all expectations. Though it may be difficult given the NC-17 rating it's forced to wear like a dog muzzle, Killer Joe is best enjoyed when approached with as few preconceptions as possible.