After losing a five-lap challenge with Big Bertha Bogliani, gum-smacking Kansas City Ramblers roller derby player K.C. Carr is traded to the Portland Loggers, managed by the suave and conniving businessman Burt Henry. On her way to Portland, K.C. stops in Fresno, CA to visit her two children, who are staying with Mrs. Carr, K.C.'s bitter mother. Although the children are proud of K.C.'s career, her youngest, Paul, is so fearful of his mother getting hurt in the rink that he refuses to speak to K.C. during her visit. Heartbroken but desperate to make a living from something other than menial labor, K.C. proceeds to Portland, where Burt introduces her to the Loggers team. Forced to play for the rival Portland team, the Renegades, until a contract dispute can be settled, K.C. is eyed suspiciously by most of the Loggers, except for Lovey, who offers her a place to stay at her houseboat. In K.C.'s first match, Jackie Burdette, the Loggers’ captain and star player, clobbers K.C., who Jackie fears has been hired to replace her. When a brawl ensues between Jackie and K.C. during the men’s game when K.C. tries to defend one of her male teammates, the crowd wildly cheers, prompting Burt to encourage K.C. and Jackie to continue their animosity on the rink even after K.C. joins the Loggers. Once alone with K.C., Burt confides that he has brought her to Portland to make her the star of the team. Although K.C. comfortably settles in with Lovey at the houseboat, the Loggers games are filled with escalating violence between her and Jackie. The animosity toward K.C. continues out of the rink with unwanted sexual advances from her male teammates and insufferable insults from Jackie. Agreeing to meet Burt for dinner one night, K.C. is easily led into a night of lovemaking at his opulent apartment. When Burt drives K.C. back to the houseboat, Lovey catches them kissing in the car, prompting Burt to trade Lovey to a Denver team the next morning. When K.C. offers to talk to Burt on Lovey’s behalf, Lovey accuses K.C. of being behind the trade in the first place. Days later on the Loggers team bus, K.C. tries to comfort the childlike Horrible Hank Hopkins, whose animal behavior in the rink prompts the crowd's laughter and humiliating taunts. Hank, who is ostracized by most of his teammates, worries that Burt will soon trade him, if he cannot, as Burt has suggested, add more "color" to his performance by overreacting to the audience's chants and hog calling. After several games on the road, the team arrives in Fresno, where K.C. visits her children and her mother, who reprimands K.C. for failing the children and not returning home. When Mrs. Carr refuses to listen to K.C.'s pleas that she just wants a "piece of the action," K.C. leaves heartbroken. Soon after, K.C. confronts Burt about trading Lovey. Burt claims that he was jealous of her friendship with Lovey and promises to make K.C. the star of his new franchise in Chicago, where she can bring her children to live with her. Days later when the tour bus breaks down, a drunken Jackie stumbles along the road accusing K.C. of using her sexual prowess with Burt to have Lovey traded. Jackie's tirade angers K.C. and in the ensuing fight, the two women tumble down an embankment onto a railroad track, where team manager Vivien and K.C. narrowly pull the barely conscious Jackie off the tracks before a train rushes by. Days later, back on the Portland rink, Hank pummels a few competitors to help K.C., who kisses him on the cheek. Emboldened by the attention, Hank plays even more aggressively, prompting the opposing team to beat him mercilessly and the crowd to throw food. K.C. tries to help the now cowering Hank, but when an opposing player throws a drink in her face, Hank goes mad, nearly killing the man and raging deliriously at the crowd. In the locker room that night, K.C.'s teammates blame her for the team's demise and for Burt's decision to make Hank a "free agent," effectively banishing him from the sport. When K.C. begs Burt to retain Hank, reminding him that he asked Hank for "color," he tells her that everyone is used in the game, implying that Hank is expendable. The next day, Burt speaks with a distant K.C., asking her to throw a one-on-one match with Jackie and promising that the "loser" will be banished to Chicago, where she will become the new franchise's star. Although Burt assures her that he loves her in his own way, K.C. accepts the deal, even though she finally realizes that Burt's real intentions are purely exploitative. After Jackie and K.C. insult each other over the intercom at the next match, a five-lap challenge is set up between the women. In the locker room on the night of the challenge, K.C., tired of manipulating her talents for everyone but herself, asks Jackie to skate in earnest to win and Jackie agrees. After four laps of hitting and swinging each other out of the rink, a fistfight ensues on the rink floor during which K.C. reaches out only inches in front of Jackie to grasp the finish line ribbon. As K.C. holds the ribbon high above her head, proud that she has won the match fairly, the crowd loudly chants her name.