Miller's determination to establish the truth takes him on a perilous go-round of Baghdad, beyond the US military's cordoned fiefdom – the Green Zone – and into territory where "the enemy" is as likely to be from his own side as from Saddam loyalists.
Greengrass, with his superkinetic camerawork and visceral sense of you-are-there immediacy, pieces together a compelling picture of a ground force trying (and failing) to order a city on the slide towards anarchy. The style has its drawbacks. In delivering what's essentially an action movie, the film's interest in nuance and ambiguity gets squashed underfoot by all the chasing and shouting and firing. I'd like to have seen more of Brendan Gleeson as the sceptical CIA spook liaising with Miller, not just for Gleeson's pudgily realistic presence but for a keener perspective on where the occupation started going wrong: was it just naivety and incompetence, or was there an actual conspiracy among the authorities to mislead? Amy Ryan is also underused as a US journalist who's been suborned for propaganda purposes, and Khalid Abdalla as Miller's informant-cum-translator becomes marginalised after a promising introduction.
There is also a problem of credibility. Miller decides to go off-reservation in pursuing his leads, apparently forgetting the small matter of the unit he's supposed to be commanding. It's exhilarating to see an American soldier flout the usual piety of "my country right or wrong" – and the suggestion here is that wrong was licensed at the top level – but you do wonder if a warrant officer would ever have the time, let alone the inclination, to play private investigator. Jason Bourne goes rogue partly because he's an amnesiac – he's trying to work out his own identity. Miller, on the other hand, only wishes he could forget the mess his country has got itself into.