A seamless weave of truth and drama, "Zero Dark Thirty" tracks the long, twisted road to Osama bin Laden’s capture, beginning on Sept. 11 and ending a decade later at another conflagration, in Abbottabad, Pakistan.

With a script by Mark Boal, who wrote "The Hurt Locker," director Kathryn Bigelow’s last feature, this new movie is a cool, outwardly nonpartisan intelligence procedural — a detective story of sorts — in which a mass murderer is tracked down by people who spend a lot of time staring into computer screens and occasionally working in the field. It is also a wrenchingly sad, soul-shaking story about revenge and its moral costs, which makes it the most important American fiction movie about Sept. 11, a landmark that would be more impressive if there were more such films to choose from.

‘ZERO DARK THIRTY’ Rated: R Opens today

The story hinges on Maya (Jessica Chastain), a spiky loner with next to no back story, no friend or family, who’s more of an ambivalent protagonist than a traditional heroine. She is introduced in the first scene during the interrogation of a prisoner, Ammar (Reda Kateb), by another CIA officer, Dan (Jason Clarke). Ammar, whom Boal has said is a composite, looks as if he has been beaten. "I own you," Dan says, "you belong to me."

Dan leaves the room with someone wearing a ski mask; this turns out to be Maya, who pushes him to continue. He does. During this scene and a second questioning, Dan knocks Ammar down, subjects him to simulated drowning and forces him inside a horrifyingly small box. The violence is ugly, stark and almost businesslike, and is largely presented without music cues or any obvious filmmaking commentary.

The scarcity of fiction films about Sept. 11 only partly explains why this movie has provoked debate. Primarily, though, it is the representation of torture — and, more important, the assertion that such abuse produced information that led to bin Laden — that has provoked outrage in some quarters. We are clearly hungry to work through this raw subject. The most difficult scenes occur early and set the grim mood and moral stakes.

It is hard to imagine anyone watching them without feeling shaken or repulsed. Some of the worst is implied: You see a bruised face, not the punch that battered it. You see a man forced into a small box, rather than hear his screams inside it. In these early scenes there is also talk — threats and pleas.

If Bigelow leaves some of this to your imagination, it is because, I assume, she knows that the viewers for a movie like this one have been following the news for the past decade. They have read the articles, books and legal arguments about the CIA’s use of what was called "enhanced interrogation" and that others have condemned as torture. Trusting the audience in this fashion is gutsy and all too rare in a movie released by a major studio. But it is an article of faith in "Zero Dark Thirty" that viewers are capable of filling in the blanks, managing narrative complexity and confronting their complicity. This is unusual territory for American moviegoers habituated to an industry that preaches simplified morality even as it turns torture into entertainment.

The scenes of Ammar in the CIA’s medieval chamber of horrors are broken into two separate time frames and occur during the first 25 minutes. And while they take up 15 of the movie’s 156 minutes, they linger, casting a long, dreadful shadow over everything that comes after. The openings of movies are always significant ("Rosebud"), and the key to understanding this one is grasping what occurs during its introductory passages. The movie actually begins with a prelude: a brief stretch of black screen accompanied by a disturbing collage of voices from Sept. 11. The first of the two interrogations with Ammar follows immediately after, a juxtaposition that asserts a cause-and-effect relationship between the void of Sept. 11 voices and the lone man strung up in a cell.

The abuse scenes are crucial to "Zero Dark Thirty" because they serve as a claim — one made cinematically rather than with speeches — that these interrogation methods are unreliable when it comes to producing actionable information. The second session ends with the screaming, babbling, weeping Ammar insisting that he doesn’t know about a coming attack as he is sealed in the box. The final moment is shot from his point of view, and what follows is a scene of a terrorist attack in Saudi Arabia. This juxtaposition of the abuse and the massacre suggests, in cinematic terms, that torture does not save lives. It is only later, when Dan and Maya lie to Ammar, sit across from him at a table, talk to him like a human being and give him food and a cigarette, that he offers them a potential lead.

That valuable clue is a false name, Abu Ahmed al-Kuwaiti (Tushaar Mehra). Called a "needle in a haystack" by one character, he becomes the lead that Maya chases over the next eight years and for much of the next hour or so of the movie. Along with her colleagues, including the equally tough Jessica (an excellent Jennifer Ehle), Maya unearths good and bad intelligence, stumbles into dead ends, unearths glimmers of hope, and endures, both at a distance and in close, frightening proximity, further terrorist attacks. She also interrogates suspects, sometimes violently (a man slaps a suspect at her command), until the political climate abruptly changes. "You don’t," Dan cautions her, "want to be the last one holding a dog collar when the oversight committee comes."

The glibness of Dan’s comment is shocking, but one of the movie’s most radical, unpleasant themes — radical because it is so unpleasant, especially for an American fiction film — is that these are employees doing a job. In reality there were those who objected to the way that detainees were handled. But this isn’t a movie about those who protested. This is about those who did not protest, who went along and who — while searching for a needle in a haystack — interrogated detainees deemed "enemy combatants" in what the former Secretary of Defense Donald H. Rumsfeld described as "a war like none other our nation has faced." The movie shows the dark side of that war. It shows the unspeakable and lets us decide whether the death of bin Laden was worth the price we paid.

"The Obama administration has claimed that torture played no part in tracking down bin Laden," Mark Bowden writes in his 2012 book "The Finish: The Killing of Osama bin Laden," but "in the first two important steps down the trail, that claim crumbles."

In his 2012 book, "Manhunt: The Ten-Year Search for Bin Laden from 9/11 to Abbottabad," Peter L. Bergen asks, "Did coercive interrogations lead to bin Laden?" Bergen reasons that "since we can’t run history backward, we will never know what conventional interrogation techniques alone might have elicited from" important prisoners. However unprovable the effectiveness of these interrogations, they did take place. To omit them from "Zero Dark Thirty" would have been a reprehensible act of moral cowardice.

There is much else to say about the movie, which ends with the harrowing siege of bin Laden’s hideaway by the Navy SEALs (played by, among others, Joel Edgerton and Chris Pratt), much of it shot to approximate the queasy, weirdly unreal green of night-vision goggles.

Bigelow’s direction here is unexpectedly stunning, at once bold and intimate: She has a genius for infusing even large-scale action set pieces with the human element. One of the most significant images is of a pool of blood on a floor. It’s pitiful, really, and as the movie heads toward its emphatically untriumphant finish, it is impossible not to realize with anguish that all that came before — the pain, the suffering and the compromised ideals — has led to this.

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By Manohla Dargis, New York Times