Trevor Garfield (Samuel L. Jackson) is a teacher in a New York City high school. After a student almost kills him in the hallway Garrfield relocates to Los Angeles, but the trouble starts again when he becomes a substitute to a class containing a tag crew by the name of K.O.S. Their murderous leader, Benny, tells Garfield that there will be no mutual respect between them. The tension mounts when a fellow teacher, Ellen Henry, confides that Benny has threatened her life. After Benny murders a rival tagger in cold blood and goes AWOL, Benny's tag partner, Cesar, takes over as class antagonist. Garfield is forced to play by the rules of the street in a pyrrhic contest between victim and victimizer.