Tiring of his self-absorbed, long-time girlfriend Melissa, former football quarterback Paul Crewe steals her Maserati. After a wild chase with the police, Paul pushes the car into the river, after which he is arrested, convicted and sentenced to two to five years at Florida’s Citrus State Prison. At the prison, head guard, Captain Wilhelm Knauer informs Paul that he leads the prison’s football team and warns him not to accept any requests from the warden to become involved with the team. Later warden Rudolph Hazen welcomes Paul, who was known in his professional days as “The Wrecking Crew,” and reveals his determination to have his prison guards’ football team win the semi-pro league championship. Although Paul points out that he has not played in eight years, Hazen asks him to be the team’s coach. When Paul refuses, Hazen assigns him to the harshest work detail in the prison. Over the next few weeks, Paul, who is well known for having been thrown out of pro-football for participating in a point-shaving scam, endures taunts from fellow prisoners who call him “superstar,” and brutal physical abuse from the guards. Despite this, fellow inmate James “Caretaker” Ferrell befriends Paul but wonders why the former athlete threw away a successful career. Paul is also supported by Pop, the prison’s oldest inmate, who, years earlier, received an additional thirty years for striking then-guard Hazen. After Paul resists Knauer’s attempt to club him during the work detail, he spends days in solitary confinement in “the box.” On his release, Paul is taken to Hazen who wants the guards’ team to have a tune-up game before the championship and orders Paul to put together a prisoners' team in four weeks and play quarterback. When Paul declines, insisting that he just wants to serve his eighteen months uneventfully, Hazen reminds him that is his eighteen months parole date, but his sentence could stretch to five years. Grudgingly accepting Hazen’s terms, Paul joins Caretaker in posting sign-up sheets around the prison yard, but the inmates are slow to respond despite their realization that a competition would allow them to rough up the guards “legally.” Disappointed by the lack of enthusiasm, Paul later welcomes volunteer and former pro-player Nate Scarboro, appointing him head coach. The next night, Paul, Caretaker and Nate break into the records office to evaluate the prisoners’ records and learn who among the playing guards have exploitable injuries. Over the next few days, Paul and Nate recruit the strongest and largest prisoners, but when Paul admits he simply wants the team to “get by,” Nate advises him that the only way to overcome Hazen’s clear intention to humiliate the prisoners, is to ensure that they win. Knowing they need the abilities of various black players, some of whom were pro-players, Paul makes a direct plea to them, but they remain suspicious of his reputation, even after black former player Granville agrees to join the team. Although the skills of the men Paul brings together vary, he and Nate begin intense practice sessions. Mistrustful of shifty, older inmate Unger, Paul turns down his plea to be the team’s manager, telling him that Caretaker already holds the position. Affronted, Unger goes to Knauer to reveal details of the prisoners’ workouts, assuring him that the only player to fear is Granville. Knauer orders his guards to goad Granville into misbehavior so they can attack him, but Granville refuses to respond to their taunts. After a particularly poor practice session, Paul happily welcomes several black prisoners who join the team for the better food and avoidance of work detail. Later during a strategy session, when Paul asks Caretaker about stealing the guards’ game films, Caretaker tells him that he will have to “pay” for them. Puzzled, Paul accompanies Caretaker after hours to the warden’s office where Hazen’s secretary, Miss Toot, provides the films in exchange for sex with Paul. At later practice sessions, Pop, Nate and Granville instruct the players how to cause the most physical damage to their opponents with the least possible evidence. One evening a few days before the game, Caretaker again asks Paul why he ruined his career and Paul admits it was for money to provide for his blind father for the rest of his life, even though his father died soon after. Meanwhile, Knauer summons Unger to cancel his privileges for offering his services to the prisoners’ team. Terrified that a return to the general prison population will result in the other prisoners’ attacking him, Unger plans revenge against Paul, who had told Knauer about his offer to help the team. A couple of evenings before the game, as Paul, Nate and Caretaker go over the starting roster, Paul asks Caretaker to retrieve medical files from his cell. When Caretaker pulls on the cell’s overhead light chain, the bulb bursts, showering Caretaker with flammable fluid and sparks which sets him ablaze. Unger, who had tampered with the bulb, then slams the cell door shut, preventing the horrified men from coming in, to prevent their friend’s death. On game day, crowds of locals attend the competition, which has been publicized as part of Hazen’s prison reform initiative. In the locker room, Hazen tells the prison team that the field is surrounded by armed guards who have been ordered to shoot any player attempting to escape. After Knauer leads the Guard Defense Unit team onto the field, the prison team is introduced as the Mean Machine, and Hazen and Knauer are shocked to see them wearing the guards’ black jersey competition uniforms, which were secretly confiscated by Caretaker before his death. The game commences with vicious clashes between the sides, and at half-time the score is the Guards 15, the Mean Machine 13. An outraged Hazen then meets Paul in the locker room to demand that he not only stifle the efforts of the Machine to win, but also provide the Guard a twenty-one point lead. When Paul stoutly refuses, Hazen reveals that Unger has confessed to murdering Caretaker but implicated Paul in the plot which would give the quarterback a minimum of an additional twenty years. Angered, but realizing that he has no other choice, Paul acquiesces. When the second half opens, Paul deliberately hesitates, allowing himself to be sacked, then throws two interceptions in a row, both of which result in quick scores for the Guard. After the Guard scores a third time, the members of the Machine realize that Paul is deliberately throwing the game. Although Paul feigns an injury to remove himself from the game, Nate and Granville express their disappointment in him. Later, after Granville is taken to the infirmary with a broken collarbone and the Guard continue in their relentless abuse of the Machine, the frustrated Paul asks Pop if hitting Hazen was worth the additional thirty years and the old man admits that it was. Going back into the game, Paul takes several brutal hits when his teammates refuse to defend him. Nate, who has not played in many years, puts himself in the game and, to his delight, scores on a pass from Paul before being injured by an intentional late tackle. The Machine players are still unsure about Paul, until he forces a touchdown, bringing the score to 35 to 27 in the fourth quarter. The Machine then kick a field goal, raising their score to 30, but find themselves pinned at the Guard’s one yard line, seemingly unable to score again. With seven seconds remaining in the game, Paul walks to the sideline, followed by his team, and exhorts them to win for Granville, Nate and Caretaker. With that, the Mean Machine return to the field and on the final play Paul makes a game winning dive into the end zone. After the team celebration, as Paul walks across the field, the furious Hazen, suspecting that Paul is headed toward the exit, orders a shocked Knauer to fire upon him. Aiming at Paul’s back, Knauer calls his name repeatedly with no response, but when the quarterback retrieves the game ball, Knauer lowers the rifle. Paul then presents the ball to the apoplectic Hazen, before heading to the locker room with Pop.