LOS ANGELES: Until the very end, she is described as “The Girl.” Even after a relentless, decadelong pursuit that leads to the daring midnight raid of Osama bin Laden’s compound, even as she unzips the body bag to verify that the bloody corpse inside is indeed that of the slain Al-Qaeda leader, Jessica Chastain’s CIA officer character is defined primarily by her femininity in this male-dominated world.

It’s probably a phenomenon with which Kathryn Bigelow is unfortunately acquainted herself, being the rare woman in Hollywood making muscular action movies – including 2009’s “The Hurt Locker,” winner of six Academy Awards including best picture and director. The latter was a first for a woman.

Even as “Zero Dark Thirty” takes an aesthetically stripped-down look at a hugely dramatic event, it shines with the integrity and decency of its central figure: a fierce young woman who’s both dedicated and brainy, demanding and brazen.

Evidently Bigalow’s approach speaks to critics. “Zero Dark Thirty” was named best film of 2012 Wednesday by the National Board of Review, after having just received the same honor from The New York Film Critics Circle Monday. NBR also named Bigelow best director and Chastain best actress.

Of course it took billions of dollars over 10 years and a multitude of people – many who gave their lives – to make this mission a success.

Bigelow and “Hurt Locker” screenwriter-producer Mark Boal have accomplished the difficult feat of taking all that time, travel, investigation and frustration and depicting it thoroughly but also efficiently. The attention to detail, to getting it right each step of the way, is evident in everything from the dialogue to the production design to the lighting.

This is pure, unadorned storytelling, an effort to recreate what happened with absolute authenticity and zero excess. Methodical and detached as it is, “Zero Dark Thirty” may actually leave some viewers a bit cold. There are plenty of moments of danger in crowded streets and claustrophobic questioning rooms, but some of the legwork is tedious and it doesn’t always pay off.

The drama is inherent from the very beginning and the emotion sneaks up on you by the end. We know what happened, and we know why it matters.

Chastain’s powerfully controlled performance – a spectacular showcase for this versatile actress’ many talents and a long-overdue leading role – is emblematic of the film as a whole. Her character, Maya (based on a real person with some tweaks to protect the woman’s identity), is described by colleagues as “a killer” upon arrival at the U.S. Embassy in Islamabad, Pakistan, two years after the 9/11 attacks.

At first quietly reserved as she watches a colleague (Jason Clarke) rough up a suspect during an interrogation – and Bigelow doesn’t shy away from the brutality of such torture – Maya soon asserts herself with her exhaustive research and inner drive.

We don’t learn much about her since she has practically no personal life. What she does speaks for who she is. At a rare dinner out one night, a fellow female colleague (Jennifer Ehle) conspiratorially asks Maya whether she’s messed around with a good-looking co-worker of theirs. Maya is appalled by the suggestion. She’s a professional. Besides, there’s no time.

She’s gotten a hold of a lead she can’t shake: the notion that following one of bin Laden’s couriers will lead to the Al-Qaeda chief. Trails grow cold, years pass, friends die in the line of duty and more attacks occur all over the globe.

Pressures run high and time is against her. She finally cracks and lets some raw feelings burst forth in a confrontation with her arrogant superior (Kyle Chandler). Also among the strong supporting cast are some actors in unexpected roles: Mark Duplass as a CIA officer and James Gandolfini as the agency’s director.

The discovery of a sprawling, heavily protected compound in Abbottabad, Pakistan, makes Maya suspicious and gives her hope.

Bigelow’s extensive staging of the May 1, 2011, raid is a prime example of virtuoso action filmmaking. Set in the dead of a moonless night – hence the title, inspired by military jargon – the Navy SEALs’ mission is both massive and intimate, a mix of ominous aerial shots of stealthy Black Hawk helicopters and infrared vision in dark bedrooms and corridors. Every bit of effort and emotion has led to this lengthy sequence, and we’re invested, too.

There’s no riding off into the sunset once the mission is complete, no swell of inspirational music. Alexandre Desplat’s score is suitably understated, too. Just a few heartfelt hugs and some tears, all of them hard-earned.