Jonathan Shale (Berenger) is a mercenary and a Vietnam veteran who returns home to Miami after a botched covert operation in Cuba in which three men from his platoon were killed. He surprises his girlfriend, Jane Hetzko (Diane Venora) at her apartment and is warmly welcomed. On the outside, Hetzko is a schoolteacher at inner-city Columbus High School, an institution with a considerable gang problem. She is particularly disliked by Juan Lacas (Anthony), leader of the KOD ("Kings of Destruction") gang. While jogging one morning, Hetzko is attacked and has her leg broken. Hetzko and Shale believe this to be related to the KOD, which prompts the latter to go undercover as an Ivy League-educated, government-affiliated substitute teacher for his girlfriend's class.