Sam Rockwell and Frances McDormand face off in "Three Billboards Outside Ebbing, Missouri." (Merrick Morton/Fox Searchlight via AP)

Sam Rockwell and Frances McDormand face off in "Three Billboards Outside Ebbing, Missouri." (Merrick Morton/Fox Searchlight via AP)

Merrick Morton/AP

In Three Billboards Outside Ebbing, Missouri, the suicide notes are funny and the racism flows freely. The lust for vengeance dies hard, and the town dwarf shoots a mean game of pool. The latest film from Martin McDonagh (In Bruges) is caustic, tender and profane. It constantly keeps us off balance, even as it never loses its own.

McDonagh and his filmmaking brother, John Michael McDonagh (The Guard), have a knack for shaking up classic Western ideas until they get giddily jumbled into something nearly unrecognizable. The justice-seeking hero in Three Billboards is one Mildred Hayes, who blazes through the film's fictional town with a score to settle. About a year ago Mildred's daughter was raped and murdered, and the culprits still haven't been caught. Played by Frances McDormand, Mildred has seen her sadness harden into fury. She displays that fury for all to see by renting three little-used billboards demanding justice from the police.

There is no Ebbing, Missouri, in real life; it's a stand-in for a certain kind of burg. The town we see here is full of lush green hills (courtesy of North Carolina) and good manners. Don't be fooled, the film suggests. This is no paradise. It's a boiling cauldron of bile.

McDonagh's dialogue is every bit as volatile and propulsive as Quentin Tarantino's. Characters curse as a matter of course, for comic effect, out of anger, or both. They streak down verbal roads, double back again and come back for more. The stellar cast, which includes Sam Rockwell as a dim-bulb cop, Woody Harrelson as the sympathetic police chief and Peter Dinklage as the dwarf with a crush on Mildred, bites into McDonagh's words like starving diners. It's hard to imagine saying these lines and not having fun.

But Thee Billboards never trades in shock value at the expense of story. This is a movie of scabrous humor and deep sadness that thrives on genuine emotions and desires: Anger, scorn, love, vengeance. Especially vengeance. McDonagh wants us to root for Mildred as she turns the drill on her dentist, kicks a couple of teens in the crotch and eventually resorts to Molotov cocktails. But he also gets us to consider the price of vengeance, and how it consumes she who harbors it. Mildred is a snarling outcast, a descendent of the Western's most famous, tormented seeker of revenge, John Wayne's Ethan Edwards in The Searchers.

The film's other outcast is Rockwell's Jason Dixon, a brutish, alcoholic cop who has a reputation for beating up black suspects and an old-school hateful mom (Sandy Martin) at home. "Things have moved on in the South," Dixon tells his mother when she suggests he do something heinous. "Well, they shouldn't have!" she barks back. The film's treatment of small-town rage and resentment is of the moment. But Dixon actually can change, and Rockwell makes this potential believable. One of the most underrated actors of the past several years, he has a gift for showing the humanity and vulnerability beneath even the most toxic façade. Dixon and Mildred spend much of the film butting heads, but in crucial ways they're two of a kind.

It's fun to watch McDonagh grow as a filmmaker. His emptiest effort, 2012's Seven Psychopaths, blurs the line between cleverness and cruelty and spends the better part of two hours chasing its tail. Three Billboards is a different animal. Under the dark comedy, or the comedic tragedy, lurks something deeply human. The movie asks questions — what is redemption? What's the right thing? What is justice? — that follow you out of the theater and resonate long after the laughter subsides.

Three Billboards Outside Ebbing, Missouri (A-)

Directed by Martin McDonagh. Rated R (violence, language throughout, some sexual references). 115 mins. At the Angelika Dallas and the Angelika Plano. 

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