Former army sniper Bob Lee Swagger (Mark Wahlberg) leaves the military after a mission goes bad and a few years later is reluctantly brought back into service by Colonel Isaac Johnson (Danny Glover) to help stop an assassination on the president. Bob is double-crossed, shot twice and now the subject of a nationwide manhunt, but after his recovery, he sets out for revenge with the help of his former partner's widow (Kate Mara) and a young FBI agent Michael Pena.