Cameron Poe, a honorably discharged United States Army Ranger, is found guilty of manslaughter in the death of an innocent but drunk bar customer while trying to defend his pregnant wife Tricia from him, and sentenced to seven to ten years. During his time in prison, he communicates with his wife and daughter while taking time to better himself. He is released on parole eight years later, and is scheduled to be flown back to Alabama on the same day as his daughter Casey's seventh birthday. Poe is arranged transport on the "Jailbird", a C-123 airplane, along with a fellow prisoner Mike "Baby-O" O'Dell and several other prisoners destined for a new Supermax prison, including William "Billy Bedlam" Bedford, Nathan "Diamond Dog" Jones, and Cyrus "The Virus" Grissom. The prisoner transfer is overseen by U.S. Marshall Vince Larkin; however, he is approached by DEA agent Duncan Malloy, who asks to put undercover agent Sims on board the plane in order to gain intelligence from one of the prisoners during flight. Larkin acquiesces but insists the agent go aboard unarmed, but Malloy is able to sneak Sims a gun during the boarding pat-down.
Shortly after the flight takes off, Jones and Grissom are able to free themselves with the help of a distraction by another prisoner, Pinball Parker, and the prisoners quickly subdue the guards and take control of the cockpit to prevent the pilot from reporting in. In the ensuing chaos, Sims attempts to threaten Grissom, but Poe, recognizing that Sims is at a disadvantage, attempts to talk the agent out of it; Sims ignores the advice and ends up dead. As Grissom organizes the other prisoners to prepare for a scheduled landing in Carson City in order to meet the required prisoner transfer numbers, Poe spots a recording device on Sims' body; he transfers it to one the guards that are being substituted for dead prisoners. Grissom insures the prison transfer goes smoothly, instructing Pinball to hide the plane's transmitter, and despite Poe's efforts, the plane leaves Carson City without incident. Poe, along with Jones, go into the hull to determine the cause of the plane's slow speed and find that Parker's body is lodged into the landing wheel compartment, having missed the plane taking off. Poe takes the opportunity to write a message on Parker's shirt to Larkin and pushes the body out of the plane, where it lands in the middle of traffic. Larkin is quickly made aware of the message; he also discovers the true identify of the "prisoners" dropped off in Carson City, and that plans for the plane's takeover were present in Grissom's cell. He and Malloy realize something is wrong, and while Malloy immediately takes off to follow the plane's transceiver, snuck aboard a sightseeing plane, Larkin recognizes that the prisoners' plane is headed in the opposite direction to the disused Lerner Airfield; he borrows Malloy's sportscar to make it to the field before the plane can land, calling in the National Guard and other forces to help secure the airfield.
Aboard the plane, Poe attempts to keep his identity secret, killing Bedford when he discovers Poe's parole letter in the personal belongings in the hull. Poe learns from Grissom that this plot was set up by drug lord Francisco Cindino, one of the other prisoners, promising that once they land at Lerner, another plane will be waiting for them to help them gain asylum in "non-extradition territory". The plane lands at the airfield, running aground, but no plane seems to be waiting for them; while the rest of the prisoners are forced by Grissom to dig out the plane, Poe explores the field to try to find insulin for O'Dell. Larkin, also on the field, happens upon the plane that Cindino promised, finding that Cindino has double-crossed Grissom and trying to flee on his own. Larkin is able to disable the plane, and the crash alerts Grissom, who shoots Cindino. The prisoners observe that armed forces are advancing on the field, and they set up a trap for the forces. Larkin and Poe briefly meet to discuss the situation before the troops arrive; Larkin goes off to help stop the troops from being massacred, while Poe returns to the plane to give O'Dell his insulin. As the troops overrun the trap, Grissom and the remaining prisoners return to the plane and take off, despite damage to the plane. Grissom discovers Poe's true identity, but before he can kill him, the plane is forced to crash land along The Strip in Las Vegas; Grissom, Jones and Swamp Thing quickly escape into the chaos. Poe and Larkin team up to follow and kill Grissom and the escaping convicts. Poe is reunited with Tricia and Casey, while telling Larkin that he now trusts him fully.
