Although Ziad Doueiri’s punchy and history-shrouded drama “The Insult” theoretically turns on the saying and refusal to apologize for two simple words, there is so much guilt and fury riddled context behind those words that they quickly become irrelevant. A Lebanese filmmaker (“West Beirut,” “The Attack”) who frequently focuses his eye on the disputatious legacy of his region’s recent history, Doueiri uses a seemingly minor conflict between two men over a gutter to show how his country’s tangled legacy of religious strife and balkanized political landscape can turn almost any interaction into warfare.

Tony (Adel Karam, a thin blade of barely contained fury) is the owner of an auto repair shop in a Christian neighborhood in Beirut. For him, his identity is a constant companion, making itself known in the political rallies he attends and the fire-breathing speeches he listens to in which Palestinians are denounced as a national scourge. The trigger for his rage appears in the form of Yasser (Kamel El Basha), the quietly dutiful Palestinian foreman of a construction crew working on the street in front of Tony’s apartment. The dance of watchful indifference on that busy street— with the Palestinians keeping a deliberately low profile (they pray in a car park where nobody can see) and the Christians ignoring them — is interrupted when water from Tony’s balcony sprays over Yasser and he notices that it’s from an illegally installed gutter. After Yasser’s request to fix the gutter is angrily rebuffed, he decides to do it anyway, only to have Tony smash the new gutter to pieces. Yasser, who until that point has seemed the calmer one of the two, calls Tony a “fucking prick,” and war is declared.

The confrontations that follow spiral quickly from a failed attempt by Yasser’s boss to get him to apologize to Tony to a punch in the gut to an overheated spectacle of a trial and genocidal threats. The rocket-fueled escalations of pride-fueled demands and invocations of various grievances would be comical if they weren’t so grounded in ugly history. It’s as though the painful past of Lebanon’s civil war, that sprawling hurricane of internecine bloodshed that lasted from 1975 to 1990 and was only ended by an extremely fragile peace agreement, remains just under the surface of even the most mundane interactions. In this Lebanon, a gutter is never just a gutter and words might as well be weapons.

Shooting at a rapid-fire clip, using highly saturated colors and taut closeups, Doueiri amplifies the clenched-jaw tenor of the conflict whenever possible. He slows down somewhat for the courtroom sequences that dominate the second half of the movie. It’s the right move, as that is where the previously so hotheaded combatants are seen to retreat somewhat in the face of the ideologues on both sides who hijack the case for their own purposes. In the hands of Tony and Yasser’s lawyers, a seemingly banal small-claims lawsuit is transformed into a symposium, on first the pained history of Palestinian refugees in Lebanon — stuck in a twilight zone of permanent refugee camps and illegal labor, blamed by Christians like Tony for having “fucked up this country” — and then the legacy of PLO terror during the Civil War, which the Christian factions believe was unjustly forgotten. (It doesn’t take long, either, for charges of Israeli collaboration to get tossed around, an ironic inclusion given that after “The Insult” won Best Actor at the Venice Film Festival for El Basha and activists declaimed the fact that the director’s 2012 picture, “The Attack” was partially shot in Israel, Doueiri was detained and harassed by Lebanese authorities.) Tony and Yasser rattle in the crossfire of a war they didn’t intend to start but clearly did nothing to stop. As Tony’s wife yells at him during a particularly mule-headed flash of pride, “You’ll burn everything but won’t turn the page.”

Although “The Insult” has its faults, from the generic score to a disappointing drift of a conclusion, it remains a powerful and thrilling example of how to create a modern political melodrama. Doueiri wrestles with the complexities of history and morality without ignoring the humanity of the individuals caught in this frightening maelstrom of a story. [A-]