Ten-year-old Tre Styles lives with his single mother, Reva, in Inglewood, near Los Angeles International Airport. After Tre gets into a fight at school, his teacher informs Reva that Tre is highly intelligent but has a volatile temper and lacks respect for authority. Worried about Tre’s future, Reva sends him to live in Crenshaw with his father, Jason “Furious” Styles, from whom she hopes Tre will learn valuable life lessons and to be able to mature, but assures him he will be permitted to return to her one day.
Tre soon reunites with his friends, Darrin “Doughboy” Baker, Doughboy’s maternal half-brother Ricky, and Chris, their mutual friend. Furious immediately has Tre rake the leaves off the front lawn, informing him of work and responsibility. That night, Tre hears his father shooting at a burglar. They wait for the police, with two officers arriving an hour later. The white officer is civil and professional, while the black officer is hostile and displays a contempt of other black men.
The next day, Tre, Ricky, Doughboy and Chris venture to a nearby neighborhood where Chris knows the location of an abandoned human body. While there, a group of adolescents loitering and drinking on a sidewalk are confrontational with the kids about their discovery of the body. One of the adolescents begins to harass Ricky and steals his football. Doughboy tries to retrieve it, but is beaten and kicked. While the older boys walk away, one of them gives Ricky his ball back. Later in the day, Furious goes fishing with Tre, telling him of his military experience in the Vietnam War. He advises Tre to never join the Army, arguing that a black man has no place in the Army. While Tre and Furious return home, they see Doughboy and Chris being arrested for shoplifting.
At a barbecue, Doughboy, now a young adult, is celebrating his recent release from jail, along with most of his friends, including Chris, who is now paralyzed and uses a wheelchair as a result of a gunshot wound, and new friends Dooky and Monster. Ricky, who is now a star running back for Crenshaw High School, lives with his single mother Brenda, his girlfriend Shanice, and their infant son. Tre has grown into a mature and responsible teenager, works at a clothing shop at the Fox Hills Mall, and aspires to attend college with his girlfriend, Brandi. His relationship with her is strained over Tre’s desire to have sex, while Brandi, a devout Catholic, wishes to wait until after marriage.
Ricky hopes to win a scholarship from University of Southern California. During a visit from a recruiter, he learns that he must score at least a 700 on the SATs in order to qualify. Ricky and Tre both take the test together, and they visit Furious at work after. Furious takes them to Compton to talk about the dangers of decreasing property values in the black community.
That night, during a local street racing gathering, Ricky is rudely bumped by someone who was recently confrontational with Tre when Tre walked across a street in front of his car. This leads to an argument which results in Doughboy brandishing a handgun. The rival group of attendees are dressed in predominately red clothing, while Doughboy and most of his crew are typically dressed in blue. Doughboy also uses the term “Cuzz” during the confrontation, which could indicate the rivalry is gang motivated.
Moments later, the rival attendee fires a submachine gun into the air from his car, causing everyone to panic and flee. Tre leaves with Ricky and notes his desire to leave Los Angeles, but they are eventually pulled over by the police. The lead officer turns out to be the same one who responded to the burglary call made by Furious seven years earlier. He intimidates and threatens Tre with his gun. Tre visits Brandi’s house, and breaks down. After she consoles him, they have sex for the first time.
The next day, Ricky and Doughboy get into a fight. While Ricky and Tre walk to a nearby store, they see the rival attendees from the street racing gathering driving around the neighborhood and in an attempt to avoid them, the two cut through the back alleyways and Ricky suggests that they split up. As Tre turns back to Ricky, the rivals’ car cuts off Ricky’s path to exit the alley. Ricky turns to run but one of the rival group shoots him twice with a double-barreled shotgun, killing him.
Doughboy, Chris, Dooky, and Monster sense danger, but catch up with Tre too late. Devastated and helpless, the five surviving boys carry Ricky’s lifeless body back home. When Brenda and Shanice see Ricky’s corpse, they break down in tears and blame Doughboy, who unsuccessfully tries to comfort them and explain the truth. That night, a distraught Brenda reads Ricky’s SAT results, discovering he scored a 710, more than enough to qualify for the scholarship.
The remaining boys vow vengeance on Ricky’s assailants. Furious finds Tre preparing to take his .357 Magnum, but convinces Tre to abandon his plans for revenge. Shortly after, Tre sneaks out to join Doughboy, Dooky, and Monster. That night, as the four search the area in Doughboy’s convertible for Ricky’s assailants, Tre asks to be let out of the car and returns home. He realizes that his father was right to keep him from falling into an endless cycle of violence.
When Tre gets home, Furious is waiting for him, but both retreat into their bedrooms without saying a word. Doughboy, Dooky and Monster find the three perpetrators in the parking lot of a fast food restaurant. Sensing their presence, the trio flees on foot, only for Monster to shoot all three with his AK-47, killing two and wounding their leader, Ferris. Doughboy exits the car and confronts Ferris. After Ferris denies shooting Ricky and insults Doughboy, Doughboy shoots him twice, killing him.
The next day, Doughboy visits Tre, and understands his reasons for leaving. Doughboy knows that he will sooner or later face retaliation for the murder he committed the previous evening, and accepts the consequences of his crime-ridden lifestyle. He plaintively questions why America does not care about the life in the ghetto, and sorrowfully notes he has no family after Ricky’s death and Brenda’s disowning of him. Tre embraces him, and tells Doughboy he has a brother in him.
The epilogue reveals that Doughboy saw Ricky buried the next day and was himself murdered two weeks later. Tre and Brandi attend Morehouse and Spelman colleges in Atlanta, respectively.