In 1980, mercenaries Danny Bryce (Jason Statham), Hunter (Robert De Niro), Davies (Dominic Purcell), and Meier (Aden Young) are in Mexico to assassinate a man. Danny unwittingly kills him in front of his young child, then is injured during the getaway. Affected by this outcome, Danny retires and returns to his native Australia.
The following year, Danny is summoned to Oman where Hunter is being held captive. He meets with an agent (Adewale Akinnuoye-Agbaje) who arranges missions for assassins and learns that Hunter accepted a $6 million job but failed to accomplish it. If Danny doesn’t complete Hunter’s mission, Hunter will be executed.
Danny is introduced to Sheikh Amr, a deposed king of a small region of Oman who wants Danny to kill three former SAS troopers—Steven Harris (Lachy Hulme), Steven Cregg (Grant Bowler), and Simon McCann (Daniel Roberts)—for killing his three eldest sons during the Dhofar Rebellion. Danny must videotape their confessions and make their deaths look like accidents, and he must do it before the terminally ill Sheikh dies. This will allow the Sheikh’s fourth son, Bakhait (Firass Dirani), to regain control of the desert region his father had ruled. If Danny fails, Hunter will be killed. Danny reunites with Davies and Meier. They agree to help him in exchange for a share of the money.
As Danny and Meier sneak into the house of their first target, Steven Harris, in Oman, Davies, in England, questions local bar patrons about former SAS members. This is reported to the Feathermen, a secret society of former operatives protecting their own. Their head enforcer, Spike Logan (Clive Owen), is sent to investigate.
After Harris has confessed on videotape, Danny and Meier take him to the bathroom. They plan to kill him by hitting him over the head with a hammer made from a bathroom tile, then leave the body to look like Harris slipped and hit his head. In the process, Harris’ girlfriend arrives, knocking on the door. While Harris and Meier are distracted waiting for her to leave, Harris attempts to break free, causing Meier to kill him hastily in a struggle.
Back in London, Davies discovers the second target, Steven Cregg, preparing for a long nighttime march in wintry weather at the Brecon Beacons mountain range. Davies creates a diversion; posing as a civilian having car problems outside the base’s fence, allowing Danny to infiltrate the base. Inside, he drugs Cregg’s coffee, causing him to go into shock and die of hypothermia during the march. Danny, in uniform, follows Cregg on the march, and makes him confess on videotape before he dies.