Vietnam veteran Major Mitchell Gant jogs along a forested path toward his cabin as a military helicopter looms overhead. When the aircraft lands, Gant grabs his shotgun, remembering his capture as a prisoner of war in Vietnam. Meanwhile, at a military briefing, a weapons strategist announces that the Soviet Union has developed an advanced, MIG-31 military aircraft called the Firefox, which is untraceable to radar technology. He explains that with the help of imprisoned Jewish physicist, Pyotr Baranovich, the Soviets created an airplane control system that can respond to the thoughts of its pilot. Back at Gant’s cabin, one of the men from the helicopter, Captain Buckholz, asks Gant to sneak into Russia to steal the Firefox, citing the need for Gant’s superior flying skills. Gant undergoes flight training and watches footage of the man whose identity he must assume: “Leon Sprague,” a drug smuggler posing as a car parts salesman. A high-ranking officer warns Buckholz that the military is prepared to abort the mission if anything goes wrong, potentially leaving Gant stranded. Once satisfied with Gant’s training, the military sends him to London, England, where he is fitted for a false moustache and glasses, and is briefed on his first mission: to meet three men on a bridge while being followed by the KGB. He receives a transistor radio, which will serve as his tracking system and only navigational tool getting out of Russia. In addition, he learns of a voice-activated black box in the cockpit of the Firefox, which he is instructed to use in the event of emergency. In Moscow, a Russian customs official questions Gant’s transistor radio, and reports his suspicions to the KGB. Russian Colonel Kontarsky meets two officials to discuss the preparation of the Firefox for flight under the supervision of Baranovich and a weapons professional, Semelovsky. That night, while being followed by KGB, Gant meets with the real Leo Sprague, accompanied by two escorts. One of the escorts, Pavel Upenskoy, beats Sprague to death, and throws him in the river along with Gant’s forged documents. As Gant’s pursuers discover Sprague’s body, the escorts bring Gant to the train station and tell him that his new identity is “Michael Lewis,” a tourist. The sounds of the rushing trains remind Gant of wartime helicopters, and trigger his post-traumatic stress. When he arrives at his stop, Gant kills a suspicious KGB officer in the restroom. Upon discovering the murder, Upenskoy becomes angry and hides the body in a stall. In a warehouse, Upenskoy gives Gant another new identity, a married man named “Boris Glazunov,” and the two men drive out of the city in a delivery truck. Meanwhile, after KGB arrests the real Boris Glazunov and inspects Leo Sprague’s body, Colonel Kontarsky attempts to determine Gant’s true identity. Explaining to Gant why he is helping the mission, Upenskoy says that he has a Jewish wife who has been in prison for twelve years. After meeting Semelovsky at nightfall, Gant hides in the trunk of Semelovsky’s car as the scientist drives home. Meanwhile, a pursuing driver shoots Upenskoy in the arm; Upenskoy drives off the road and escapes on foot. At his house, Semelovsky instructs Gant how to enter the military base, remove the Firefox’s pilot, and board the aircraft. He reveals that the hangar also contains a second prototype plane, which needs to be destroyed by fire before Gant steals the aircraft, lest the Soviets pursue him. In addition, Gant must think in Russian in order for the telepathic plane controls to work. Colonel Kontarsky determines that Gant is a foreign agent, suspecting that he must work for NASA or the U.S. Air Force. In Soviet military uniform, Gant enters the hangar and knocks the pilot, Lt. Colonel Voskov, unconscious, stuffing his body in a locker. While Gant showers, KGB officers arrive to inform hangar security that Gant is a spy and they must search the premises. Just as Colonel Kontarsky learns of Gant’s true identity, one of the scientists working alongside Baranovich sets a fire in the hangar. KGB officers kill Baranovich, and Gant boards the Firefox, clearing the runway. Still lying in a field nursing his injury, Upenskoy sees the plane take off, and raises a gun to his head to commit suicide. While recording a message in the plane’s black box, Gant receives a transmission from the Soviet First Secretary, telling him to return the aircraft if he wants to remain alive. Gant refuses, and flies south. The First Secretary determines that Gant can only fly 3,000 miles before he runs out of fuel, and orders that KGB obliterate the aircraft as soon as it is spotted. However, General Vladimirov believes that Gant is flying a route meant to deceive them. Although the prototype aircraft, undamaged in the fire, will not be armed and ready for another hour, the officers determine that they can use their missiles’ infrared technology to follow the heat of the Firefox’s fuel emission along Gant’s projected path. Gant quickly realizes their strategy and fires a reverse missile to destroy the weapons, before blowing up multiple helicopters near a Soviet naval base. Sometime later, original Firefox pilot Voskov boards the prototype plane and flies after Gant. In the ocean, an American submarine rises to the surface to receive Gant; he lands on the ice and refuels. The Soviets pick up the submarine’s radar signals and instruct Voskov to find the Firefox. When Gant takes to the air, Voskov follows close behind, chasing him through the mountains. Gant spins out of control, pummelling downward as he squeezes his eyes shut at the memory of his near-crash in Vietnam. Gant lowers the wheels and fires a rear missile, which demolishes Voskov in the second plane. Free of his pursuer, he enters the coordinates of his destination and flies into the clouds.