Based on the true life experiences of poet Jimmy Santiago Baca, the film focuses on half-brothers Paco and Cruz, and their bi-racial cousin Miklo. It opens in 1972, as the three are members of an East L.A. gang known as the "Vatos Locos", and the story focuses on how a violent crime and the influence of narcotics alter their lives. Miklo is incarcerated and sent to San Quentin, where he makes a "home" for himself. Cruz becomes an exceptional artist, but a heroin addiction overcomes him with tragic results. Paco becomes a cop and an enemy to his "carnal", Miklo.
Mousie and Sad Girl are childhood best friends in a contemporary Los Angeles poor Hispanic neighborhood. But when Sad Girl becomes pregnant by Mousie's boyfriend, a drug dealer named Ernesto, the two become bitter enemies. While their dispute escalates towards violence, the violence of the world around them soon also impacts their lives.