The British film industry never found a Vietnam-type genre in the violence of Northern Ireland, maybe because there wasn’t the same sense of us and them: the republicans were never as far-off and exotically faceless as Hollywood considered the Viet Cong to be. But this traumatic era – almost over, but not quite – might yet prove a rich seam. Screenwriter Gregory Burke and first-time feature director Yann Demange have made a cracking movie debut with ’71, a behind-enemy-lines war movie reeking with bad blood and bad faith, perhaps best described as an action-conspiracy thriller. It is interestingly free of the tone that dramas about the Troubles traditionally assume: a tone that you might call tragical correctness.

The film is set in west Belfast in the early years of the conflict, a year before Bloody Sunday; a time when Northern Ireland was still routinely referred to on television news as “the province”, like an outpost of the Roman empire.

Its central figure is played by Jack O’Connell, a terrific actorwith the charisma of a young Albert Finney. He is Gary, an English lad from Derbyshire who has joined the Parachute Regiment, and who perhaps finds in the army the comforts of a replacement family. At the beginning of the decade, he is shipped out to Belfast, where the army must participate in the fiction of being merely present to assist the civilian police (the Royal Ulster Constabulary, as they were then called) in their duties, rather than directly imposing martial law.

A house-to-house search off the Falls Road goes horribly wrong; the resulting confrontation triggers a riot situation in which Gary is left behind by his retreating unit. He finds himself in a no-man’s-land where that well-honed phrase “the enemy within” appears to apply both to friend and foe. It is a world in which the authorities are running high-level informers and supplying arms to loyalist paramilitaries to maintain a deniable, proxy war. Gary’s commanding officer, Lt Armitage (Sam Reid), finds himself at odds with the furtive, plain-clothes intelligence operative Captain Browning (Sean Harris); and the Provisionals’ fiercely committed Haggerty (Martin McCann) and the eerily blank-faced Sean (Barry Keoghan) are plotting against their own chiefs. Meanwhile, a former army doctor on the republican side may be Gary’s only chance: he is Eamon, played by Richard Dormer (notable for his excellent portrayal of Terri Hooley, the punk music promoter in Good Vibrations).

Facebook Twitter Pinterest The Guardian Film show team review ‘71

This is a taut thriller, with great control of action and pace, and an outstanding re-creation of the west Belfast war zone. There are moments of dry-as-dust comedy, as when one member of a bomb-making team asks another how he’s going to get up in the morning: after all, he’s not getting his alarm clock back. For his nail-biting chase sequence, Demange was probably influenced by the Gerry Conlon riot scene at the beginning of Jim Sheridan’s In the Name of the Father (1993) and, of course, Paul Greengrass’s superlative Bloody Sunday (2002). But, despite its downbeat ending, and perhaps as a result of its 21st-century vantage point, ’71 does not have the usual issue-movie piety. It is naturally different to Steve McQueen’s Hunger (2008) – which is about another aspect of the Irish situation – but also very different to, say, Ken Loach’s Hidden Agenda (1990). Despite its obvious seriousness, this is closer to the cynicism of a straightforward crime thriller. The concept of republican agents in the pay of British intelligence is reminiscent of James Marsh’s Shadow Dancer (2012), but the subject is presented with far more detachment.

Where the film strikes a false note is at the beginning, when the paras are repeatedly told that where they are going is not abroad, that Belfast is “in the United Kingdom” and that “they are not leaving the country”. I’m not sure that it would have been spelled out like this: it is an anachronism, born of our more modern suspicion that the Paras were encouraged to behave as if they were suppressing an uprising in a far-flung part of the empire. Nowadays, with modern Belfast running “black taxi tours” excursions around former IRA strongholds, the world of ’71 seems far away. But as drama, Demange and Burke make it seem very immediate and very real.

• ’71: Berlin 2014 – first look review