French television director Yann Demange (E4 miniseries “Dead Set,” 2008) makes his feature film directorial debut with “‘71,” a period thriller set amid an ethno-nationalist conflict across Northern Ireland famously dubbed The Troubles. Jack O’Connell (“Starred Up,” 2013) plays Gary Hook, a fresh recruit to the British Army who’s deployed without protective gear to support the Royal Ulster Constabulary’s (RUC) inspection of homes for weapons in 1971 during the unrest’s early years. A protest breaks out, unraveling into a violent mob that forces Hook to separate from his teammates. Bloody, bruised, and fearing for his life, he must try to escape the nightmare before it eats him alive.

The period setting and overall visual aesthetic of “‘71” would make you wonder if it’s more war drama than political/crime thriller. As the tension and pace gradually ramp up, any doubts you may have are thrown out of the window because all you can focus on is Hook’s treacherous, life-threatening journey through what’s essentially a never-ending source of terror. While Scottish playwright Gregory Burke, who makes his screenwriting debut with “‘71,” focuses his screenplay primarily on its embattled protagonist, multiple subplots running simultaneously alongside feature the varying murky agendas of its different supporting characters.

Notable among them include Military Reaction Force (MRF) Captain Browning (Sean Harris; “Prometheus,” 2012), Sean (Barry Keoghan; “Stalker,” 2012), and James Quinn (Killian Scott; “Calvary,” 2014), all of whom cover different points in the spectrum of moral ambiguity. Keoghan, in particular, delivers a terrific turn as an easily influenced young adult who simultaneously questions if he’s doing the right thing every step of the way. Others, including Charlie Murphy (“Philomena,” 2013) and Sam Reid (“The Railway Man,” 2013), are excellent in their respective supporting roles.

However, the performance that grabs you by the gut in “‘71” is its lead. O’Connell delivers a masterfully restrained performance as Hook and successfully shows his dynamic range as an actor through his vivid brushstrokes of vulnerability and terror throughout his character’s runtime. Hook’s claustrophobic experience through the film’s narrative is visually enhanced greatly by Tat Radcliffe’s (“Love Bite,” 2012) frenetic cinematography and Chris Wyatt’s (“Dreams of a Life,” 2011) razor-sharp film editing. A breathlessly directed set piece involving a chase doesn’t just set up the gravity of Hook’s situation; it also showcases the excellent work Radcliffe and Wyatt pitch into “‘71,” helping realize Demange’s singular visual storytelling style.

“‘71” wastes no time, throwing you right in the middle of the action, and never lets go for a single second throughout its 99-minute runtime. Demange’s visceral direction of Burke’s multilayered screenplay delivers the goods on what ends up being a non-stop political/survival thriller whose strength lies in how its makers use the resources at hand to craft a hyperkinetic work of art that’s both heartbreaking and terrifying in equal measure. The director’s debut is among the best in cinema this year. Highly recommended.