“Get In” is a taut, troubling and topical French thriller almost utterly undone by its over-the-top finale.

In movie buff shorthand, it’s a John Schlesinger’s “Pacific Heights” that devolves into Sam Peckpinpah’s “Straw Dogs” — devolves, and keeps on devolving.

Aurélien Molas and Olivier Abbou’s script gets into issues of masculinity, race, bullying and a justice system that fails to deliver justice.

At every turn, history teacher Paul, played by Adama Niane (“Gang of the Caribbean”) is pushed, misused and tested. It started before the movie begins. His marriage to Chloé (Stéphane Caillard of TV’s “War of the Worlds”) is in trouble. And then, after a nice long road trip vacation in his father’s old RV, they’re denied entrance to their home.

As outrages go, that’s primal. Not only has the recently-evicted couple — Sabrina (Marie Bourin) was their nanny — changed the locks and denied them entry after house-sitting for them. They call the cops and Paul is roughed up and taken in when he is understandably outraged at how his kindness has been repaid.

This “true story” takes the family into the French legal system, with judges kicking the decision hither and yon — that’s what covering your bases and having a “contract” with the house sitter gets you — days becoming weeks and then months.

Their lawyer is all reassurances, “They have no right to be there” and “You’ll get your house back, I assure you.” And yet, “You can’t evict them” and “The council bans evictions in the winter.” As they’ve been warned by the cops, “Don’t try to do this by yourselves — three years in prison” well, what are they to do?

Paul, given to storming out of meetings or, in the case of the marriage counselor, skipping them altogether, is increasingly outraged.

We think, “How far can he be pushed?” But we, like his wife, like Sabrina’s hulking husband Eric (Hubert Delattre) size up the thin Franco-African and say, “What’re you gonna do about it?” (in French, with English subtitles).

The RV park where they have to stay might have the answer. Mickey (Paul Hamy) is a rough character. But we can see the look he and Chloé share, even if Paul doesn’t notice.

They have history. And judging from his tattoos, and hers, it was rough and ready. Mickey is bad news all around as he talks Paul into “guys’ night out,” drinking strip club binges topped off with a little redneck animal cruelty.

Yeah, totally a thing in France, too.

Mickey taunts Paul — “You’re a victim because you decided to be one.”

Chloé shrugs with a “You don’t get it. We can’t do anything. So accept it.”

Will he be goaded into action by Mickey, or tamed into putting the marriage and their family first and hoping for the best from a court system that doesn’t guarantee that?

Director Abbou and his cast make us furious on Paul’s behalf, then fearful of Paul’s actions. The conversations with the squatters are all “No comment, no comment…You need to LEAVE.”

Paul ends far too many talks with legal figures with the phrase “You can’t be serious!”

Paul’s attempts at resisting this incessant bullying — even his bigger students in class figure they can push him around — make us feel his futility.

As this isn’t America, Paul can’t drive straight to a gun store to even up the odds. Just having this thought it part of the film’s troubling way of playing with the psyche.

“Get In,” titled “Furie” when it was released in Europe, works on you and works on you and builds towards something that the finale suggests is the true consequence of crossing that line into violence.

You can’t control it. Once unleashed, it consumes you, your enemies and those you love.

Not a bad parable for our times, with “might makes right” and “superior firepower” increasingly the rule as first justice and fairness break down, then civility, then law and order.

But the Big Finish here looks like something horror studio Blumhouse would cook up. “Get In” doesn’t get quite all the way in because of it.

MPAA Rating: TV-MA, graphic violence, explicit sex, nudity, alcohol and drug abuse

Cast: Adama Niane, Stéphane Caillard, Paul Hamy, Marie Bourin and Hubert Delattre

Credits: Directed by Olivier Abbou, script by Aurélien Molas and Olivier Abbou. A Netflix release.

Running time: 1:37