Streets don’t get much meaner than those of Belfast back in 1971 as the British army all but occupied the territory, caught up in what amounted to terroristic street fights between Catholics and Protestants with few truly innocent bystanders in the middle. Everyone took sides, no matter how reluctantly, and in most cases everyone knew all of the players, so all you had to do was take one good hard look into the eyes of the person in front of you and you knew their allegiances.

Gary Hook (Jack O’Connell), an anonymous soldier in the British army, trains hard but is no standout. In an earlier age, Hook would be the standard-bearer for the military as a collection of force, a real stiff-upper-lip band of brothers, where you help the man next to you cross the mile marker or take the ridge because the only way each individual soldier succeeds is if everyone succeeds. Hook isn’t a lone wolf — an army of one — despite what little backstory we get from screenwriter Gregory Burke (who earned a BAFTA Film Award nomination for Outstanding Debut by a British Writer, Director or Producer, which he shared with ’71 director Yann Demange). He’s an older orphan with a younger brother still in the boy’s home where he was raised. He loves his brother, who he visits before shipping off for duty.

Now, I know, based on what I’ve said thus far, Hook looks for all intents and purposes like a young Liam Neeson or a baby-faced soldier-boy of few words (think Clint Eastwood) who is simply waiting for the opportunity to prove himself in the theater of battle. And he certainly gets his chance when his unit, under the command of a rather green lieutenant (Sam Reid), receives orders to back up local police in a neighborhood search for weapons.

The obviously tense situation results in a standoff with an angry mob and the soldiers working without the protection of their riot gear — which their lieutenant decided to leave behind so that they could project a more humane face and presence. When a soldier loses his gun, Hook and another soldier head off in pursuit, only to get swallowed up in a crowd of rock-throwing protesters. The soldiers get a momentary reprieve from a woman who calls the crowd out, but all bets are off once the soldier with Hook gets shot in the head at point blank range. The troops get recalled and Hook is all alone and definitely on the hook.

The true tension here stems from the forces aligned around Hook. In fact, the standout trait in Hook is an intriguing passivity. He falls into the hands of several factions in this fractured community and he has no stake in their game. At one point, he crosses paths with a savvy young neighborhood boy (Corey McKinley) — an obvious reminder of his own younger brother — who immediately recognizes him as a soldier, and fires a quick question at him to find out if he’s Catholic or Protestant. It is such a fundamental query, like asking someone if they are human during an alien invasion, but Hook has no answer. His experience is so outside this situation, even basic knowledge of the importance of choosing a side, that the boy has no other choice but to take this stray under his protection.

What happens to Hook during this hellish night is akin to a paper bag drifting through various crosscurrents. He gets injured, placing him at the mercy of others, but he wafts along with moments of awareness — he identifies shadowy figures, men from his regiment working as plants/spies in the neighborhood — but he is never able to use this knowledge as a means of extricating himself from the dire straits he’s in. The best decisions Hook makes, in extreme cases, involve simply going on the run. Yet, this movement allows him to remain inactive, unable to take control of his own fate.

This stands in sharp contrast to our typical expectations for action thrillers. We have been conditioned to expect heroes with a sense of agency or, at the very least, characters that resort to violence when there are no other options. Demange and Burke flip the script, quite literally, but the dramatic imperative of the narrative never wavers. We don’t need to see Hook transform himself into a superhuman (and indestructible) killing machine to engage with him or the story on some deeper level. Real depth exists here, in the internal dilemmas that each character that comes into contact with Hook faces. How everyone responds to Hook, either by helping him, using him as a pawn or attempting to remove him from the equation, illuminates some aspect of their side’s perspective and turns ’71 into a far smarter thriller than the wham-bam power plays currently seeking to gain the upper hand at the box office. (Opens Friday) (R) Grade: B+ (tt stern-enzi)