Sean Penn, fresh out of his star-making supporting role as stoner Jeff Spicoli in Fast Times at Ridgemont High, plays Mick O'Brien, a 16-year-old Irish hood from Chicago. While most of Mick's crimes involve snatching purses, vandalism, and getting into brawls, he aspires to bigger and better things, which leads him to attempt ripping off a rival hood, Paco Moreno (Esai Morales). Everything goes wrong: Mick's partner and best friend (played by a pre-Ferris Bueller Can't Lose Alan Ruck) is killed, and Mick, while trying to escape the police, accidentally runs over and kills an eight-year-old boy who happens to be Paco's kid brother.
Because he's under 18, Mick is sent to the Rainford Juvenile Correction Facility rather than a state prison for adults. However, as the film makes clear, this "juvenile correction facility" is not a place where troubled kids are reformed, but rather a place where they grow tougher, angrier, and more prepared for a life of adult crime. Most of the wardens and counselors seem to have resigned themselves to the role of zoo keepers, with the exception of Ramon Herrera (Reni Santoni), a former gang member who talks tough to the inmates, but holds out hope for some of them, especially Mick.
In his second time in the director's chair (his first was 1981's Halloween II), Rick Rosenthal relies quite heavily on Steadicam and crane shots. The scene in which Mick is first brought into the main hall of the reform school is a good example, as it allows us to take in the entire space—the multiple levels, the gray walls, the leering faces of the other inmates—putting us right in Mick's shoes. Given his disposition at the beginning of the film, it is hard to imagine that Mick could be a particularly sympathetic character, but Penn's performance is so forceful in its naturalism that we feel for him. In some ways, writer Richard Di Lello (Colors) stacks the deck a bit by making Mick's crime of manslaughter truly "accidental," but the filmmakers never shy away from the fact that Mick is a bad kid. Thus, there is a genuine sense of character development as Mick makes hard decisions during his stint, evolving from an angry and aimless boy to a young man who will take responsibility for his life.
Mick's cell mate, a small, wiry Jewish kid named Horowitz, is played by Eric Gurry, who gives the character both a much-needed sense of humor (thus inducing a few laughs into the otherwise grim material) and an element of danger (he is at the reform school because he firebombed a bowling alley in an attempt to kill some kids who beat him up). In a story like this, there are always the toughest thugs in the group, in this case a couple of brawny sadists named Viking (Clancy Brown) and Tweety (Robert Lee Rush). As soon as their alpha male status is established, the plot demands that Mick's first step toward defining himself will be to stand up to them, but the way in which he does it is so brutal and sudden that it feels surprising.
Paco is eventually incarcerated at the same reform school, thus leading to an inevitable showdown between him and Mick.