I’m starting to get concerned about Jack O’Connell, the talented breakout Brit star as well as seemingly the current valedictorian at the Mel Gibson School of On-Screen Masochism.

First there was "Starred Up," in which he played a violent prison inmate; then he starred in the two-hour beatdown-palooza that was "Unbroken." And now there’s "’71," which doesn’t even get five seconds in before it’s punching O’Connell in the face and dragging him through mud. And that’s the comparatively fun, relaxing part of his cinematic gauntlet. Somebody needs to give this dude a romantic comedy or at least a hug. He needs 50ccs of Nancy Meyers stat.

If he insists on essentially self-flagellating on screen, though, at least it’s in the service of a quite good movie with "’71," a taut, bloody-knuckled behind enemy lines thriller with Ireland’s long Catholic versus Protestant conflict as its grim, haunted backdrop.

O’Connell stars as Gary Hook, a rookie British soldier barely through with training before he and his fellow squad mates are jettisoned off to Belfast to help quell the growingly violent tensions. Under the watch of an almost equally unseasoned lieutenant (Sam Reid, "The Railway Man"), Hook and his company tenuously accompany RUC officers on a midday raid through Catholic houses, searching for guns and brutalizing those who don’t comply.  

Signaled by the locals clattering garbage lids (an ominous, eerie detail), a crowd quickly arrives and with it increasing unrest. Angry shouts escalate into spit, which escalates into rocks. During the growingly violent chaos – with at least one soldier knocked unconscious and another shot point-blank in the head – Hook winds up chased deep behind Catholic lines, where there’s seemingly a burning car on every corner and a posse of angry Nationalists stalking down every road.

With no means of communication and little friendly aid in sight, Hook’s alone in finding his way back to safety – all the while alliances around him constantly shift. Young Nationalists, angry and wanting to fight, clash with older Nationalists trying to keep them out of the violence. A group of undercover MRF agents originally on Hook’s side (led by Sean Harris, the pot-smoking scientist from "Prometheus" here sporting some fine ’70s hair) now want him dead after he plays witness to a bomb plot gone wrong. And all Hook wants is to survive the night and get home.

Making his feature screenwriting debut, Scottish playwright Gregory Burke takes a page from the likes of "The Sniper" – Liam O’Flaherty’s famed short story about Irish brothers in battle – and crafts a chase through a brutal Irish Civil War chapter that’s equal parts gritty intensity and nuanced humanity.

Shaky battle lines cut right across the street and through homes (an early map shows how tight quarters the fight is). Small accidents and incidents – a bombing mixes around many of the allegiances in play, regardless that it was the result of a mere mishandling – send shrapnel into allies, enemies and innocents alike. Fresh faces litter both sides of the battle; Hook and his squad are all right out of camp, while in Belfast, young rebels and kid soldiers appear on both sides – all eager to do right, but uncertain what right is in battle. Conscience hangs over every death, brotherhoods battered and broken in such an intimate fight. The war machine rages on, however, and as one helpful doctor cautions to Hook, "You’re all just meat."

"War is hell" isn’t the most original message, but "’71" makes it sting with the tragic particulars and heartbreaking messiness of such a tight-knit conflict. All of Burke’s moving allegiances and motivations can become an unwieldy, densely accented tangle, occasionally losing Hook in the process. But what the film slightly loses in tension bouncing from the straight-forward perspective of being alone surrounded by, at best, the unknown, it gains in complexity. It hauntingly depicts war as, in Harris’ oversimplified words, "a confused situation," one where there are no winners – save for those who get as far away as possible.

It’s a grim and gutty story that plays impressively like it’s based on real events, a tribute to the writing and to director Yann Demange. The feature film rookie pulls off an impressive Paul Greengrass imitation, effectively using grainy visuals, anxious held-held camerawork and sharp editing to drop the viewers into his sharpened cinderblock of a thriller. The action sequences – especially an early chase deeper into Belfast with bullets splintering into bricks – hum with immediacy thanks to the nimble camerawork and vigorous editing, and the early riot is a strong piece of escalating tension as well, Demange capturing the growing, heart-pounding chaos without becoming incoherent. It marks a strong debut, balancing the script’s grim-faced human elements with intense thrills.

The acting ensemble is strong all around – especially Harris, whose inky, needling eyes and gaunt figure (to say nothing of his ’70s wig) make for him an imposing and slithering player. However, "’71" is O’Connell’s show, and it’s a strong physical performance. He’s clearly mastered the art of on-screen pain; during a tough surgery scene, for instance, he makes you feel every stitch.

He’s constantly magnetic, conveying a lot with a little (there’s a great brief moment after the riot where you can see a quick smile of relief vanish remembering he’s far from fine) which is good because there’s little here in Gary Hook. Much of the interesting character work is going on around him; he’s merely the ragged flag avoiding capture, and much like in "Unbroken," he's left almost solely defined by his survival.

The young actor still does impressive work, investing the character with quiet humanity, horror and toughness that keeps the audience involved. He's a strong center in an equally strong, rough and raw-nerved little war thriller. It’d just be nice to see him take on a role that isn’t essentially just a boxing bag filled with powdered bones and mashed cartilage nobly enduring for our entertainment.

In fact, O’Connell's next movie is "Tulip Fever," a dramatic period romance featuring paintings and the tulip mania of 17th century Amsterdam. For his sake, it sounds like just what the doctor ordered – though considering his resume so far, his character probably has punishing allergies or something.