In the late 1980s, with the Irish civil conflict at its most treacherous, 22-year-old Martin McGartland (Jim Sturgess) is recruited by the British police to infiltrate and spy on the Irish Republican Army (IRA). Working his way up through the ranks as a volunteer for the IRA while simultaneously feeding information to his British handler, McGartland lives his life under the constant threat of being exposed as an informant. This double life, a secret kept even from those closest to him, begins to unravel and the threat of exposure becomes a harrowing reality when McGartland is captured and tortured to within an inch of his life. Against the odds, he manages a daring escape. To this day, Martin McGartland is still on the run. Based on the shocking real life story.