Matt Damon film riffs off Amanda Knox

Running time: 140 minutes. Rated R (language). In theaters.

As vibrant and colorful as Marseille, France, is, something you don’t often see there is a plaid flannel shirt.

But that’s pretty much all Matt Damon’s average American character, Bill, wears in the engrossing drama “Stillwater.”

Bill’s life, however, is hardly ho-hum. An Oklahoma oil rig worker, he isn’t traveling in the seaside city to take in the sights and nosh on foie gras terrine; his college-aged daughter, Allison (Abigail Breslin), has been imprisoned for a year in Marseille for the murder of her roommate she claims she didn’t commit. She’s serving a five-year sentence during the prime of her life.

I’m going to take a wild guess and say Amanda Knox will not be watching “Stillwater” this weekend.

What director Tom McCarthy’s intriguing film — which is a tad overlong — deftly explores are the cultural barriers that prevent us from achieving basic goals, such as solving a murder, and connecting with people unlike ourselves. The story is a lot more nuanced than France vs. America.

Matt Damon says going to backyard barbecue was "eye-opening" in his preparation for the movie "Stillwater."
Bill, played by Matt Damon, is determined to prove that his daughter didn’t murder her roommate in “Stillwater.”
©Focus Features/Courtesy Everet

On one of Bill’s prison visits, Allison tells him she heard that a man named Akim was in town bragging that he’d stabbed a woman a year earlier. The French police were never able to find Akim during the investigation to corroborate her story. The media thinks she made him up. Bill tries to reopen the case with this new information, fails and then goes rogue to hunt down the alleged perp.

But what makes “Stillwater” so unpredictable and unnerving is when it turns, for a sublime moment, into a romance.

He meets an outspoken local woman named Virginie, played by the marvelous French actress Camille Cottin, who helps him translate conversations on his quest to clear his kid’s name. Eventually he gets a job there, moves in with Virginie and forms a bond with her little daughter, Maya (Lilou Siauvaud).

Matt Damon becomes the father figure for a young French girl while trying to clear his biological daughter's name in "Stillwater."
Matt Damon becomes the father figure for a young French girl while trying to clear his biological daughter’s name in “Stillwater.”
©Focus Features/Courtesy Everet

In time, they become a sweet family unit, but with the inescapable feeling that, with Allison’s murder conviction and Bill’s ingrained Americanness, we know they can never really work out.

The film finds a sustained calmness before tensing back into a thriller near the end.

Damon does a good job reining in his emotions, which sets up a potent contrast between his Great Plains bashfulness and the French’s forthright honesty. He also has a believable paternal relationship with Breslin, who, imprisoned, looks like a porcelain doll forgotten in an attic.

Cottin is the main attraction here, though. Brilliant on the French comedy series “Call My Agent,” which can be seen on Netflix, she is every bit as good in this mostly English, American-made drama. Her motives and deeper thoughts are kept mysterious, and we’re left desperate to know how she truly feels about this man and his mission.

It’s a quality that should make her a big star here.