Elroy "Junior" Jackson (Jeff Bridges) speeds through the backwoods of rural North Carolina in his Mustang, arriving home to help his father Elroy, Sr. (Art Lund) and brother Wayne (Gary Busey) put their moonshine whiskey into bottles. When the boys joke about a policeman named Collins, their father admonishes them to treat the man with respect. On that night's delivery run, Junior evades arrest by listening to the police on his CB radio and eventually running a roadblock which forces Collins to jump into a watery ditch. The next day, Collins retaliates by blowing up Mr. Jackson's whiskey distillery and arresting him.When Wayne informs Junior that his humiliation of Collins has put their father in prison, Junior goes to the jail with a lawyer, attempting to take responsibility for the incident, but his father stoically accepts his fate. The lawyer advises Mr. Jackson to renounce bootlegging in court to lessen his sentence, but Mr. Jackson refuses on principal, arguing that everyone at city hall drinks his whiskey.The next day, Junior talks to a racing promoter named Hackel (Ned Beatty) about entering the local demolition derby in order to raise money for his father's legal defense. Hackel ridicules the backwoods boy, but Junior persists and is allowed to compete. Junior's brother and friends help him prepare an old car for derby day with a spike to project from the grill so that he can ram his competitors' vehicles, an innovation that excites the crowd and wins him $200.Invited to the next derby, Junior replies that he will enter the stock car race instead and again Hackel scoffs at him. To prove his skill, Junior times himself on the track that night and is so fast that he is allowed to enter. During the race, Junior amazes the crowd with his fearless driving and wins first prize. Afterward, Junior drives to city hall to attend his father's trial, but discovers that the trial has already ended and his father has been sentenced to a year in prison for refusing to denounce moonshine.Unaware that his mother (Geraldine Fitzgerald) is in attendance, Junior wins his eighth race on Hackel's track, which ends with another driver attacking Junior over his aggressive maneuvers. After the fight, Hackel brands Junior a troublemaker and orders him never to return, to which Junior retorts that he is a star and will race at the more prestigious Hickory racetrack.That night, worried about Junior's safety, Wayne and his mother urge him to take a job as a garage mechanic, which he angrily refuses due to the low pay. During Junior's next visit to the jail, when his father tells him that "one man's foolishness is the breath of life to another," Junior realizes that only his father understands him and gives him his trophy.Needing money for a faster car, Junior continues delivering moonshine, now in a truck with a tank that he and Wayne have equipped with a release valve that dumps the whiskey onto the road if the police get too close. However, when the sons proudly tell their father about the invention, he chastises them for antagonizing the police.Junior arrives at the Hickory racetrack to announce to the owner Morley (Gregory Walcott) and racing star Kyle Kingman (William Smith) that he will win the next race, but Morley, who knows Junior's reputation, replies that he has declined Junior's entry. In response, Junior surprises Morley by producing a pit pass and a rule book that states he has a right to qualify.After successfully completing his trial run, Junior goes into the office where he meets Morley's friendly assistant and secretary, Marge Dennison (Valerie Perrine), and thanks her for sending him the pass and rule book. As Junior signs the entry papers, Marge tells him about his motel accommodations and puts his name on the list for the buffet, adding that he can bring a guest. When Junior invites Marge to dinner and she replies that she has a date, he grins and says he does not discourage easily.That evening, when Junior checks into the motel he finds that Marge has gotten him a discount on his room and has flowers delivered to her. As he is getting out of the shower, Junior, wearing only a towel, is flustered when Marge knocks and enters, thanking him for the flowers and flirting while he dresses for dinner.At the buffet and party, Marge dances with Kingman while Junior sees driver Rick Penny (Lane Smith) arguing with his manager, Burton Colt (Ed Lauter). When Penny complains to Junior afterward, Junior disdainfully suggests he work for himself and as Junior drives Marge home, he derides the other drivers as hired jockeys.After dropping Marge off, Junior goes into a recording booth where he makes record for his family, telling them about Hickory and finally apologizing to his father, saying that he loves him, but throws the record in the trash as he leaves. Back in his room, Junior calls Marge and is shocked when Kingman answers, but is later cheered when his friends show him their new team jackets emblazoned with his name.On the day of the race, Junior sees Marge waving from the stands and sadly realizes that she is waving at Kingman. The race begins and Junior pulls ahead with his friends cheering him on, while Penny falls behind as his manager bullies him over a radio. When Junior's car catches fire he is unhurt, but is unable to complete the race, which Kingman wins. Impressed with Junior's driving, Colt takes advantage of the destruction of his car by offering to make him one of his drivers, but Junior refuses to be bought, vowing to get a new car and beat Colt and everyone else.While celebrating Kingman's victory with him, Marge meets his wife, Trina (Erica Hagen), who makes it clear that Marge should end the affair with her husband. Calmly accepting this, Marge turns to Junior and they proceed to her apartment where they have sex for the first time. They are startled when their post-sex romantic conversation is interrupted by Kingman unlocking the door, but Kingman smiles and tosses his key to Junior for future use.Later back home, Mr. Jackson returns from jail after being paroled early for good behavior, but when his sons show him their new underground still, he angrily destroys it, saying he does not want Junior to risk his racing career by bootlegging. When Junior retorts that he needs money for a new car, his father slaps him, saying that Elroy Jackson, Jr. will find a way.Seeing no alternative, Junior offers to drive for Colt in exchange for 50% of the prize money. Colt inflexibly counters with his terms of 30% and demands that Junior wear his uniform, drive his car and use his crew. Junior eventually accepts and begins the Hickory 500 race with Colt coaching him through an earpiece, which Junior soon discards and proceeds to race his own way.Junior and Kingman compete for the lead throughout the grueling contest until Junior finally triumphs. In the winner's circle, Junior is joined by his friends and Colt. As they are celebrating, Marge congratulates Junior and although he is relieved that she is no longer with Kingman, he sadly watches her leave with another driver. When Colt threatens to dock half of Junior's $3,000 prize money for insubordination, Junior grabs the trophy, saying that his racing talent gives him the power in their relationship. Junior then informs Colt that he will continue racing for him only if he can retain 60% of future prize money and use his own car and crew. Colt reluctantly accepts the deal.In the final scene, as his brother and friends enjoy skipping stones at a local pond, Junior walks alone into a press conference as flashbulbs pop and he is asked by the reporters where he, Junior Jackson, is going to race next.