When, late on a Sunday night, Barack Obama went on television to announce that Osama bin Laden, mastermind of the September 11th terrorist attacks, had been killed by Navy SEALs, Americans, or at least those paying attention, were seized by a strange dichotomy. There were those who celebrated — most famously, right outside the White House — and those who felt that maybe celebration was the wrong response, inexact and tasteless. Our biggest bogeyman — an emblem, terrorism incarnate — had been taken out, but did we really want to cheer for death? And what did Osama bin Laden amount to, exactly, in 2011, nearly ten years after he'd pulled off his most infamous act? We were quickly distracted from that quandary by the action-movie plot of it all, as we learned details about a place called Abbottabad, about the mighty SEAL Team 6, about the strange things found in bin Laden's compound (porn, namely). But what was lost in all these exciting bits of narrative, perhaps, and in the torn emotions of a country unsure of what, exactly, it had "won," were the real nuts and bolts and process of the years-long hunt for this Big Bad Man. And so, in an effort to sift through the historical data and explain to us how this all went down, director Kathryn Bigelow has made Zero Dark Thirty, a long and sober and thoroughly compelling account of CIA people treading moral lines and sifting through piles of nothing to find one seven-foot Saudi.

Our follow car through this nearly-a-decade span is a young CIA officer named Maya, played with theatrical vigor by Jessica Chastain and based on a real person — a lot of this movie is real, and in new and surprising ways, which makes it newsy and relevant here and now, three weeks before its release. At the beginning of the film, Maya is new to the field, arriving in Pakistan and going straight to a brutal water-boarding interrogation. She's hesitant and off-put — she looks away at particularly gnarly moments — but Maya is not, it's carefully pointed out, without spine or conviction. That the film opens with such a graphic depiction of torture is both unnerving and oddly welcome. Yes, OK, here you go. Right out front for all to see. This is how information was found, this is the anonymous, spirited away origin of the great patriotic deed. And Bigelow is careful not to editorialize on the matter. We are simply seeing what happened. But there is a sense, throughout the opening sequence, that bigger issues are afoot. Whether Bigelow or her screenwriter Mark Boal are pro-torture in cases like these, or vehemently against it entirely, is not really the point; that America employed such ugly means, by way of our version of the good guys, very much is: The usefulness of torture is one of Zero Dark Thirty's several hard and unflinching and deliberately presented truths. Maya is eventually inured to this brutality (and by extension so are we), singlemindedly determined as she is to wrestle some justice into the world.

We continue to watch Maya over the course of about eight years, as American foreign policy creaks and groans under the weight of two wars and leads grow cold or disappear around dark corners. The bulk of Zero Dark Thirty is fits and starts, progress met with terrible setbacks. Maya befriends, in an aloofly professional sense at least, some of her colleagues, all played by strong actors like Jason Clarke, Harold Perrineau, and the indispensible Jennifer Ehle, and they aid her in her search while also warily detecting a bit of mania. (A comparison to Homeland's Carrie Matheson is tempting to make here, but I think that silly show doesn't really have a seat at this serious, real-life table.) Maya, though, is our Final Girl, and as she loses colleagues to violence and the siren song of an easy life in bureaucratic Washington, her focus grows ever sharper. In one of the film's strange moments of emotional exposition, Maya tells a special-ops guy that she believes she alone has survived and maintained because she is meant to see this thing to its end. There's a whiff of righteous, almost religious conviction in that sentiment, but Bigelow doesn't dwell on it for long. We only get to know the inner Maya in brief glimpses; most of our time is spent peering over her shoulder and watching her pursuit.

In its length and up-close intensity, Zero Dark Thirty struck me as almost a geopolitical version of David Fincher's Zodiac, another movie about an individual consumed with a hunt that most others have given up. Of course that story ends, excruciatingly, with nothing but a big and shadowy question mark, whereas we know where Zero Dark Thirty is ultimately headed. Still, Bigelow and Boal make some salient points by highlighting Maya's near-crazed fixation and alienation; what good is chasing down one symbol at the expense of ignoring all that it represents? Of course other arms of the CIA were investigating elsewhere while Maya was buried in a pile of satellite images and nommes de guerre, but the film does point to unthwarted post-9/11 terrorist attacks like the 7/7 bombings in London as a way of dismayingly suggesting that the Western world's intelligence agencies were perhaps looking in the wrong direction, toward revenge and reprisal rather than larger-reaching prevention. But somehow, despite all that, we are still instep with Maya, even as she suffers setback after setback, essentially relegated to the Fox Mulder crackpot wing of the agency.

Eventually, though, she gets a break. While trying to find a guy who she believes to be bin Laden's chief courier — his liaison to the outside world — Maya realizes she may have just stumbled on bin Laden himself. Her hunch is credible enough to lure her colleagues back to the cause, and watching these only lightly fictionalized versions of competent people do their tricky detective analysis is both satisfying and a little scary — the way they can glean usable, important information from a satellite image's tiniest details should perhaps give us all pause about being so thoroughly observable. Though the eventual raid on the Abbottabad compound is a foregone conclusion, the lead-up to the event is still freighted with a kind of logistical suspense. By now we've spent two hours rattling around with Maya, so the notion that she might finally be proven right feels of vital importance. And of course she is, and the film's climax shows us the SEALs — among them Joel Edgerton and a disarmingly goofy Chris Pratt — doing their thrilling, deadly work. It's honestly difficult to not forget one's political convictions at this point in the movie, so awed are we by the majesty and efficiency of our sleek, technological armed forces. Oh, how those stealth helicopters whir through the night! My, how precise and forceful these highly skilled killing machines look as they bust open doors and clear rooms! Bigelow does not shy away from the fact that these men are invading a home filled with noncombatants — namely wives and children — and yet we are still, maybe shamefully, rah-rah-ing along with our guys. I suppose that, as in the analysis scenes, we may simply be cheering for jobs done as well as they can be done, but I also felt an uncomfortable twinge of jingoism rising up in me while I watched this hushed, nighttime raid. That's not Bigelow's fault, she maintains her objective gaze throughout, but perhaps a trigger warning should be put into effect. Caution: This probing and solemn film may cause unintentional spasms of hawkish patriotism.

But, again, for the most part Zero Dark Thirty is done with a sharp eye and a documentarian's remove. Not to say that there aren't exciting, dramatic flourishes that could only be captured in a scripted film — there are plenty of crisp and harrowing action sequences, for example — but Bigelow does tend to stay mostly in the realm of the real, of the factual. (Maybe too factual, according to some claims that the government was overly accommodating of Bigelow and Boal's requests for information.) It's a shame then, that the person at the center of all this literalness is played with such pinched staginess by Chastain. A fine actress, Chastain is so new and so suddenly huge on the scene that it was easy in her initial flurry of roles to assume that she could do anything. But, alas, Zero Dark Thirty finds some of Chastain's limits; her innate, fine-boned elegance and earnest, projecting Juilliard voice don't quite work in dank interrogation rooms and ho-hum dusty offices. She certainly has moments of strength throughout the film, that proud patrician face curling into delicate knots of frustration, but all told I can't help but feel she was miscast. We need someone sturdier and less, I dunno, fanciful to be our avatar throughout this grand mission. Chastain holds the camera, but she never quite gives life to all the shop-talk dialogue. She's not helped by a few silly expositional lines and preachy monologues, either.

Still, Bigelow's film resonates and connects on multiple levels. We have the prodigously answered intellectual curiosity about how this guy got found, there's the cool vision of investigative and technical mastery, and there's a quieter vein of introspection that carries the film to its mysterious final shot. Bigelow closes her film not with a grand pullback on the World Trade Center or some bit of follow-up text. Instead we are with one person, on an airplane, heading to destination unknown. There's a sense of weariness here, and also a faint note of dissatisfaction. What have we just watched, really? Or rather, what does what we just watched actually signify? That we spent these millions of dollars to finally track down this one man has been used as a warning to other would-be terrorist leaders, as a key talking point for a beleaguered president, and perhaps as a means of closure for those grieving for loved ones lost eleven years ago. And yet, it was just a man, despite Maya's continued insistence that he represented something bigger. I don't think the air of anticlimax and unsettlement in the film's final moments is unintentional. To mangle a line from Saving Private Ryan, another movie about determined people searching for an individual in the midst of anonymous chaos, in all this mess, what does one man really mean?