As Jason Clarke’s CIA torture monkey prepares to dehumanise a swarthy captive – an emir of the terrorist fraternity, he makes a declaration: “this is what defeats looks like”. It would be tempting to read that as triumphalism, though premature, but the line reading is cold; the atmosphere in the room, poison. Katherine Bigelow, who’s cannily foreshadowed these scenes with an aural montage from 9/11, resensitising us to its horrors by removing those ubiquitous, numbing images, with thanks to Michael Moore, invites us to speculate on who this defeated party might be.

Is it the suspected jihadist, stripped of all rights and dignity, now suffering, perhaps justly, for his involvement with the hijackers, or America, who’s traded its much trumpeted moral superiority for brutal pragmatism? There are members of the American Academy for Motion Picture Arts and Sciences and US government lackeys that are incensed that Bigelow’s film dares ask the question. They’re imbeciles. It’s the job of effective cinema to ask questions; your conscience, if the filmmaker’s minded not to manipulate you too forcefully, provides the answers.

Bigelow’s made a sober, uncomfortable picture about the decade long search for Osama bin Laden: a film that clothes itself as an intelligence procedural while focusing on the personal cost to those charged with bringing the al-Qaeda head and Islamic Fascist in Chief to “justice”. Why the inverted commas? Because it isn’t clear that justice, as we used to think of it, in those quaint, dreamy afternoons before bin Laden’s retinue of failed humans re-set the bar on egoistic suicide, has any part to play in this manhunt.

Due process and a fair trial are the furthest things from the mind of Jessica Chastain’s zealous field agent. Recruited young and at first green from the sight of a half-naked man being folded into a box, she soon hardens her heart to the realities of “detention” and other euphemisms.  By the time Mark Strong’s agency go-between, incensed at the lack of progress, bangs the desk and reminds all concerned that, “your fucking job is to bring me people to kill”, any pretence that the war on terror is a battle for America’s soul has been abandoned. That war, you feel, is lost. What’s left? Intelligence gathering, compromise and reprisal. This is the first great conflict of the 21^st century and it isn’t clear that the belligerents really know what it’s about.

Zero Dark Thirty is a long account of what are alleged to be “actual events”, which may not be the same as those which are, in the broadest sense, true. Bigelow is once again the reserved stylist of The Hurt Locker – there’s that pretence to realism, the fly on the wall mentality that maintains the critical distance between film and audience while demanding their absolute attention. Every so often that earnestness tips over into testosteronic excess, Chastain a little too pumped, in scenes that uncomfortably recall Bigelow’s early and more colourful work. The path from action maestro to filmmaker of record is, we’re reminded, strewn with IEDs.

In a movie long on detail but short on humanity, the final third, the assault on the Abbottabad compound, where bin Laden spent his final years, sharing with operatives’ families and a haul of VHS tapes (including the United States’ copy of Teen Wolf), is almost light relief. It’s a thoroughly absorbing conclusion, which despite the outcome being well known, is suffused with tension, thanks to Bigelow’s well-judged decision not to embellish and film much of it from the perspective of nervous soldiers in glorious night vision.

When the end comes for the medieval-minded madman, it’s quick and divested of the theatre one might dread in the depiction of a moment of historical significance. The understatement sums up the entire enterprise. In the absence of cinematic grandeur and didacticism, we’re left as empty and as lost as Chastain’s agent as she boards a symbolically empty plane for an uncertain future. What are we to think of the so-called War on Terror: just retribution or a campaign that’s acutely focused our attention on the hypocrisy and ideological infirmity that was there all along? You, as ever, must decide.