“Rosebud.” It’s the single word that’s key to the mystery at the heart of “Citizen Kane.”“Stillwater.” It’s the single word that’s key to the mystery at the heart of the picture of the same name. No way is that meant to signify an equivalence between one of the greatest movies of all time and writer-director Tom McCarthy’s flawed drama, starring Matt Damon as an American on a highly personal mission in the French port city of Marseille.

Though like “Kane,” “Stillwater” aspires to be a meaningful study of a complex individual. Unfortunately, while it aims for profundity, by the end, it dives into absurdity.


Its title notwithstanding and though it starts in Oklahoma, “Stillwater” mostly takes place in Marseille. It’s there that Damon’s character, Bill Baker, an Oklahoma oil field worker, travels on a quest to free his daughter, Allison (Abigail Breslin), from a French prison.

The circumstances surrounding her incarceration were, McCarthy acknowledges, patterned after the case of Amanda Knox. Like Knox, Allison has been convicted of the murder of her female roommate in Marseille. She insists she’s been wrongly accused and pleads with her father to persuade the French authorities to reopen the case. (Knox’s ordeal played out in Italy and she was later exonerated.)


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The reason she’s in France has to do with the fact that she and her dad are deeply estranged. She’s fled Oklahoma to get as far away from him as possible.


He’s a salt-of-the-earth fellow: goateed, burly with a bit of a beer gut, taciturn, with a baseball cap on his head. Not a red MAGA hat, however, though he’s clearly a red-state kind of guy. Trump is mentioned but once in the picture and very briefly at that.


McCarthy, best known as the writer-director of the 2016 best-picture Oscar winner “Spotlight,” turns “Stillwater” into a combination character study and detective story. Bill dedicates himself to finding an elusive man his daughter claims is the real killer, but he’s stymied by his limitations.


Literally a stranger in a strange land, he doesn’t speak the language and doesn’t understand French culture or the country’s legal system. Among his other limitations: He’s a high-school dropout, he has a tough time holding down a steady job and he’s had drinking and drug problems in his past. That history has alienated him from his daughter (her grandmother raised her after her mother died) and even landed him in prison years ago, which is why, when asked if he voted for Trump, he declares he didn’t, asserting that as a felon he wasn’t allowed to vote.


Damon’s performance is careful and restrained as he slowly reveals Bill’s flaws. Bill is a guy who keeps himself on a short leash. He appears mild-mannered much of the time, but there’s anger simmering just below the surface that erupts when the language barrier and other stresses of his situation get the best of him.


A sympathetic Frenchwoman, Virginie (Camille Cottin), comes to his aid and offers to be his translator after he befriends her precocious 9-year-old daughter, Maya (Lilou Siauvaud). The warming relationship between Bill and the mother and her child gradually melts his reserve. He feels himself being redeemed as romance blooms and he develops fatherly feelings toward Maya.


The acting throughout is first-rate with Breslin doing a good job of portraying Allison’s harsh anguish at not being able to trust her father and Cottin bringing an easy sophistication to her work as Virginie. Young Siauvaud comes across as rather too precious.