Matthew McConaughey shows his wild side in KILLER JOE

Matthew McConaughey has successfully burst out of his rom-com treadmill and made his mark in some dark and fascinating projects this year. In BERNIE — the Richard Linklater true-story film in which mortician Jack Black kills rich lady Shirley MacLaine but pretends she’s still alive — McConaughey had fun as the heat-seeking D.A. thrust into the case who makes things even more strangely comical. In MAGIC MIKE, he was Dallas, the owner and MC of a male strip club, a guy for whom squeals and screams are the preferred soundtrack of life. And now, he gets his most offbeat role of all in KILLER JOE, the William Friedkin-directed adaptation of the Tracy Letts play that centers on white trash at each other’s throats, with McConaughey’s character calling the dirty shots.

KILLER JOE has a young drug dealer (Emile Hirsch) getting thrown out by his trashy mother, which prompts his decision to get her bumped off so he can collect on the insurance. He calls on Killer Joe Cooper (McConaughey), a Dallas lawman turned hitman who’s supposedly the best at this kind of rubout, and who promptly lays down the law about the secrecy issues. But Hirsch doesn’t have the money, so Killer Joe simply dives on Emile’s little Sister (Juno Temple) as a form of preliminary payment.

Emile’s dad is played by Thomas Haden Church, who’s terrific in a role Nick Nolte surely would have played 15 years ago. And his stepmom is Gina Gershon, who’s a natural here, turning in such a vivid performance as a sleazeball that I wish she’d been around in the 1940s to have appeared in some real film noir classics.

This movie is set in a world of trailers, pizza stops, howling dogs and lots of nudity. (Gershon blithely shows her bottom half and McConaughey his back half — it’s practically MAGIC MIKE again for him.) But despite the ambient touches, the movie moves in fits and starts, feeling a little tedious as it aims to shock but doesn’t really find the right tone.

And then comes the climactic scene where McConaughey confronts Gershon about her slippery behavior and makes her do something to fried chicken that is already pretty legendary in cult film circles. The scene is hilarious, harrowing and a leap beyond even Tarantino and the Coen brothers for sheer dysfunctional power plays. After that, alas, the movie goes even more over-the-top to a place of sheer ridiculousness.

And yet, while KILLER JOE doesn’t kill, McConaughey is very good as the cowboy-hat-wearing man with the deadpan. It’s a dark little feather in his cap — a long way from FOOL’S GOLD.