In the 1980s, when the Irish civil conflict was at its most treacherous, 22-year-old Martin McGartland (Jim Sturgess) was recruited by the British police to infiltrate and spy on the IRA.
He lived his life under the constant threat of exposure and subsequent torture and death, yet he continued because his information saved many lives. He enjoyed the buzz until he was discovered and had to escape against all odds. Inspired by a true story, to this day he is on the run.