'71 Jack O'Connell, Paul Anderson, Richard Dormer. Directed by Yann Demange. Rated R. Opens Friday.

Without a detailed familiarity with the various factions involved with the Irish Troubles in the 1970s, some parts of the thriller ’71 may be a little hard to follow. But director Yann Demange and writer Gregory Burke succeed at making those fine distinctions less important than the visceral danger that the main character, British soldier Gary Hook (Unbroken’s Jack O’Connell), is in from moment to moment, no matter who happens to be pursuing him. Hook gets separated from his unit on his first mission into the volatile war zone of 1971 Belfast, Northern Ireland, and has to figure out whom to trust as he attempts to make his way through unfamiliar streets and back to his barracks.

Demange keeps the tension high throughout nearly the entire film, starting with the moment Hook’s inexperienced unit is deployed into the middle of a burgeoning riot. Tracking the shifting allegiances among the secondary characters can be a little difficult, but the disorientation mirrors Hook’s own confusion, as the people who seem the most trustworthy are often the first to betray him. Demange and Burke value thrills over political commentary, although Hook’s terrifying single-night ordeal proves equally effective at illustrating the inherent futility of the conflict.