The book was released in 1993.
High school senior and basketball star Samuel Styles is known to his friends and teammates as "Slammer", "Sambot", "Samgod", or simply "god" due to his physical size and athletic prowess. Over the past four years, he has led the boys basketball team at Greenspark Academy to the state title numerous times, while Greenspark's girls' team – led by misfit Deanie Gauthier – always lingers just shy of victory. In his final year at Greenspark, however, Sam announces that this will be the year that both basketball teams, boys and girls, bring home a trophy.
To this end, Sam makes a tenuous effort to befriend the girls' basketball star, Deanie "the Mutant" Gauthier. Despite her abilities as an athlete, Deanie is a social outcast even amongst her fellow players. She is known for her reckless behaviour on the court, her distinctive unfeminine look (she shaves her head, sports multiple tattoos, and wears a trademark series of chains that connect her numerous earrings to her nose-ring), her promiscuity, and her drug use. Sam is repelled by both Deanie's belligerent, off-putting attitude and her reputation, especially since Sam is soon branded with the same reputation as their teammates, coaches, and school officials begin to believe the two are dating.
Sam quickly learns that Deanie comes from an abusive home where her alcoholic, drug-addicted, passive mother allows Deanie's likewise alcoholic live-in boyfriend Tony to molest and batter the girl. Due to neglect, Deanie must work part-time jobs and often steal in order to keep herself fed and clothed. Although he is concerned for Deanie's well-being as a human being, Sam is nervous about getting involved in such a volatile situation with a girl who rebuffs his every offer to help her. Instead he tries to help Deanie in secret by offering her rides to school in bad weather, giving her cast-off clothes, feeding her from his own lunch pail, and even going so far as to partially renovate an abandoned mill to give Deanie a safe, warm place to practice basketball. He also pressures her to give up drugs and cigarettes in order to stay eligible for basketball. While Deanie dismisses all Sam's efforts as nagging, she begins following his advice in private. Sam believes that Deanie is still living her usual wild lifestyle and frequently gives up on her in disgust, only to learn through the high school grapevine that Deanie is, in fact, cleaning up her act.
The boys' and girls' teams begin to work together on the practice court, where the girls must toughen up in order to defeat the harder-playing boys. The boys' coach objects to the new arrangement, claiming that his team will get soft through the easy effort of playing against the girls, while the girls' coach believes this advantage may be what her team needs to win the state championship. Both coaches, as well as the high school principal, realize that the relationship between Sam and Deanie is at the root of the change, but only Sam is warned away from Deanie, leading Sam to believe that those in charge have given up on Deanie as a wasted effort. This makes Sam even more protective of Deanie, and the two become lovers.
Deanie's mother's boyfriend Tony, too, becomes aware of Deanie's relationship with Sam and reacts by beating her violently, ending with Deanie having her own jewellery smashed into her face. Wounded, she flees to the safety of the renovated mill, where Sam later finds her when he becomes concerned that she might lose her basketball eligibility by missing school. Sam takes Deanie to the hospital, where her jewellery must be surgically removed from her face. The hypocrisy of the school officials and law enforcement, who only move in to protect Deanie after it is too late, galls Sam, although he realises that he, too, bears the blame for not reporting suspected abuse.
Deanie refuses to press criminal charges against her stepfather, who goes free. During her recovery, she moves in with Sam and his family, where she finds herself confused and often angry at their loving, functional household compared to her own life of abuse. Both she and Sam are frustrated that Deanie's facial lacerations mean that she will be unable to complete her basketball season, until Deanie learns of a new design of protective mask that may let her compete. Sam redirects all the earnings from his after-school job to purchasing the mask for Deanie, and both students lead their respective teams through the finals to win the state championship.
Immediately after the finals, however, Tony kills Deanie's mother and Deanie seems to drop back into her old habits. Sam finds her once more in the old mill, high on marijuana, playing in the dangerous rafters. Sam climbs after her and pleads with her to come down. Deanie does so while Sam waits above to make certain she is safe, but when she reaches the ground, she is ambushed and attacked by Tony, who had been hiding there while on the run from the law. With no way to reach them in time, Sam jumps from the rafter, landing on top of Deanie's stepfather and bringing down with him a load of old brick and debris.
The book fades out, only to resume on a scene a few years later. Sam and Deanie have chosen to go to the same college together. While Sam still undergoes physical therapy for injuries from his fall, he may be able to play basketball as a walk-on later in the year. Comments from two of their professors indicate that the two young people have set up house together, despite the controversy of their high school careers, and it is implied that Sam and Deanie are in love and willing to work hard to remain together.