Everyone knows war is hell, but not all directors know how to bring that concept to life. In their pursuit of literal-minded accuracy, they forget about such seeming irrelevancies as lighting and pacing and full-blooded human beings. Britain’s Yann Demange, a first-time filmmaker of French Algerian descent, makes no such mistakes, and a better thriller is unlikely to see release this year.

After sketching in a few basic details, he plunges full-bore into the heart of sectarian darkness. Jack O’Connell, who tends to gravitate toward physically demanding roles (Starred Up, Unbroken), plays Gary Hook, an army recruit who makes the jarring segue from British countryside to burned-out Belfast at the height of the Troubles.

During his very first operation in a republican stronghold, things go terribly awry, and he finds himself alone in hostile territory, a situation that echoes Carol Reed’s 1949 noir Odd Man Out with James Mason, except Demange is a more kinetic, visceral filmmaker (as he did for Steve McQueen’s lacerating Hunger, Belfast composer David Holmes provides the eerie, insinuating score).

Hook quickly finds that every group—Catholics, Protestants, even his own regiment—has factions within factions, so he puts his trust in people who may have ulterior motives. But Demange is no cynic, and help comes from all sides.

It would be giving too much away to reveal whether he makes it out of this morass alive, only that you’ll be pulling for him every step of the way.