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.

A businessman sinks $200 million into a special project to help fight brain cancer. As part of this project, medical biologist Susan McAlester rather naughtily figures out a way to genetically enlarge shark brains, so that cancer-battling enzymes can be harvested. However, the shark subjects become super smart and decide they don't much like being cooped up in pens and being stabbed with hypodermics, so they figure a way to break out and make for the open sea...