Jim Carroll (Leonardo DiCaprio) is a Catholic high school student at St. Vitus High School in New York. His life in high school centers around his love for basketball. One of the players and his best friend Bobby (Michael Imperioli) dies of leukemia. Then coach Swifty (Bruno Kirby) disillusions him with his advances toward him while he's in the locker room shower. To cope with his life falling apart, he turns to drugs. When Jim's mother (Lorraine Bracco) finds out he's doing drugs, she kicks him out onto the streets. From there he spirals downward into the world of drugs and prostitution, all the while, writing everything down in his diary. He finds redemption when he returns to his love for basketball and plays a game once in a while with Reggie (Ernie Hudson) who used to live on the streets and do drugs, himself.