In 1977 Africa, Veteran mercenary Allen Faulkner trains and leads a group of fifty hired soldiers in an attempt to rescue deposed President Julius Limbani. After rescuing the president, the team is double-crossed and caught in the open, where Faulkner's men are attacked by a hostile airplane. Faulkner tries to escape the country with the handful of survivors in an antique Dakota aeroplane. His best friend Rafer Janders is shot in the leg and left unable to catch the taxiing plane. With hordes of ferocious Simbas about to overtake him, Janders calls for Faulkner to kill him, which he regretfully does.
In 1982 London, the only surviving Nazi leader in captivity, Rudolf Hess has secrets that could destroy the careers of prominent political figures, secrets an international news network will pay any price to get. Robert McCann is arguing with Michael Lukas about the delay of a planned rescue of Hess as Allen's brother Alex Faulkner arrives for a meeting with network executives. Michael and his sister Kathy ask him to free Hess, and he refuses, recommending John Haddad as a substitute. Haddad is a former Lebanese-American soldier turned mercenary. Having just avoided Palestinian hitmen in London, Kathy and Michael hire him to free Hess and get him safely out of West Berlin.
Haddad stakes out Spandau Prison as a jogger, drafts plans of the outside of the prison and joins a construction team to get access to the prison-guard entrance. He plots out the guards' timed patrols and drafts floor plans of the hallways and cell blocks. When he leaves the prison with the construction crew, Haddad is abducted by Karl Stroebling, a Nazi working for the Soviet Union. Stroebling and his thugs torture Haddad with a plastic bag to obtain details about his mission. Haddad overpowers his captors and escapes.
While recovering in hospital, Haddad is questioned by British Colonel Reed-Henry, suspicious he is there to rescue Hess. Haddad leaves the hospital with Kathy for Bavaria to plan the mission without interference from Stroebling. Haddad enlists his old mercenary comrade Faulkner, a former British Army officer working as an assassin and an expert marksman, to watch his back. As romance between Haddad and Kathy blossoms, the trio returns to West Berlin to find that Reed-Henry will help Haddad release Hess. Reed-Henry claims that the British secretly want to get rid of Hess because the old man's presence is a reason for the Soviets to have military in the British sector. Once again, Stroebling's thugs attempt to kill Haddad but with Faulkner's help they kill all but one of them.
Meeting with Reed-Henry to discuss his plan, Haddad agrees to hand over Hess to the colonel in exchange for help from Regimental Sergeant Major James Murphy. Murphy, an ex-warden at Spandau Prison, informs Haddad of the prison routine and helps make the mercenaries look like British Royal Military Police. Stroebling offers to remove a contract on Haddad's life in exchange for Hess and the death of Faulkner. Haddad refuses and Stroebling leaves frustrated.
The plan is finalised, with the news network, Reed-Henry and Stroebling each believing they will receive Hess. Part of the plan involves a staged traffic accident, so Haddad employs fairground wall-of-death rider Pierre Helou to perform the deliberate crash. Attempting to force Haddad into a vulnerable position using blackmail, Stroebling kidnaps Kathy. In exchange for guaranteeing her safety, Haddad must have a member of Stroebling's gang, Patrick Hourigan, join the rescue group. Haddad and Faulkner are now joined by Michael and Lebanese mercenaries Joseph and Jamil Koury. The group, including Hourigan, are trained by Murphy. During one of Faulkner's fever spells, Hourigan substitutes Faulkner's medication with LSD tablets causing hallucinations.
After the training is finished, Hourigan taunts Murphy about an IRA ambush in which he participated. Murphy shoots Hourigan dead, putting Haddad in a dilemma over Kathy's safety. Haddad enlists his final team members, Arab businessman Mustapha El Ali and his employees, to take a few minor parts in the rescue. To appease Stroebling, Haddad offers Michael as extra insurance. Haddad must rescue Michael and Kathy from the clutches of Stroebling. Michael creates a diversion for Kathy and him to escape but is killed during the struggle when guard Devenish retrieves his handgun and shoots him. Moments later, Haddad kills the guards and rescues Kathy. The plan goes ahead as scheduled but Pierre is killed in the staged accident.
Hess is sedated with an anaesthetic, switched with the look-alike corpse from the other ambulance and placed into a waiting jeep. At the rendezvous point at the Kaiser Wilhelm Memorial, Reed-Henry tries to intercept Hess but discovers that he has been duped into killing Stroebling disguised as a guard. Kathy, Haddad and Faulkner take a drugged Hess to and from a football game. Together with the Austrian fans, they travel to an East German airport to flee to Vienna. They succeed by killing a curious East German customs officer. Reed-Henry confesses to his Russian superiors that Hess has escaped with his rescuers and is nowhere to be found. He accepts execution by being shot with his own pistol.
Haddad, Kathy and Faulkner take Hess to a hotel in Vienna. He overhears Kathy talking on the phone to McCann about the rescue and Michael's death. Hess, knowing that he is being exploited, tells Kathy, Haddad and Faulkner that he has no desire to be a part of modern society. He has regrets about the millions of deaths. Haddad and Faulkner try to talk him into accepting his freedom but he insists on going back to Spandau to live out the rest of his life. The following day, Haddad, Kathy and Faulkner take Hess to the French embassy, where he turns himself in. A newspaper article in the following days tells a story about a false rumour of Hess' escape.