In Chicago, Illinois, teenage thief Mick O’Brien robs two people and buys a pistol on black market before returning home to his neglectful, alcoholic mother. Elsewhere in the city, Paco Moreno and his friends, Carlos and Pablo, enter a dark alley, where they arrange to deliver a briefcase filled with stolen pharmaceuticals to an African American street gang the following Saturday night. Nearby, Mick’s friend, Carl Brennan, watches from his apartment window. At school the next day, Carl tells Mick of Paco’s drug deal, suggesting that they intercept the briefcase. Moments later, Paco arrives and makes disparaging comments about Mick and his girl friend, J. C. Walenski. The couple trades insults with Paco before heading to class. After school, Mick and J. C. make love in her bedroom, and she expresses fear that Mick’s life of crime will end tragically. Mick assures her that he is in no danger, especially from the juvenile justice system. On Saturday night, Mick and Carl don black clothing and ski masks as they prepare to rob Paco. Mick hands Carl a pistol with the promise that the weapon is more of a threat than a necessity. The boys steal a car and follow Paco, Carlos, and Pablo to the designated meeting place, with Paco’s little brother, Pacito, trailing behind. Mick and Carl cross the street with their pistols drawn, in plain view of the arriving gang members. The ensuing gunfight leaves Carl, Carlos, and one of the gang members dead. As police sirens are heard in the distance, Mick returns to the car and races from the scene, accidentally hitting and killing Pacito before crashing into a parked van. A judge, convinced that Mick is a sociopath, sentences him to Rainford Juvenile Correctional Facility, until he is deemed able to re-enter society. Mick arrives at Rainford with a younger boy named Terrell, and they are assigned to Dormitory C, which houses serious criminals, such as murderers, armed robbers, and rapists. As they enter the dormitory, the other boys gather around Mick and Terrell and spit on them as they walk to their rooms. Mick’s roommate is Barry Horowitz, is an undersized boy genius who killed three people with a homemade bomb. Mick also meets “Viking” Lofgren and his roommate, Tweety, the designated “barn bosses” for the dormitory, who, according to Horowitz, “keep the rest of the animals in line and give out the work details.” Viking takes an immediate dislike to Mick and puts him on bathroom duty. Later, Mick meets with counselor and former gang member Ramon Herrera, who tries to gain the boy’s trust. When Tweety rapes and murders Terrell, Warden Bendix launches an investigation, but none of the inmates, including Mick, admits to witnessing the incident, even though it happened in plain sight. Regardless, Viking and Tweety accuse Mick of being an informant and threaten him with bodily harm. Mick prepares by filling a pillowcase with cans of soda, and when the boys accost him, he beats them unconscious with the pillowcase. Following a brief period in solitary confinement, Mick learns that his triumph over Viking and Tweety has won him the position of barn boss, with Horowitz as his lieutenant. Unable to intimidate Mick, Viking turns his wrath on Horowitz, who surprises the bully by attacking him in the mess hall. However, when the warden places Horowitz in solitary confinement, the boy’s fear of isolation is revealed as he becomes hysterical. Meanwhile, in Chicago, Paco is arrested and convicted after beating and raping J. C. When Mick hears of the rape, he escapes Rainford and makes his way to J. C.’s home, where Ramon Herrera is waiting to escort him back to Rainford. Upon his return, Warden Bendix promises to withhold punishment if Mick can set a good example for his fellow inmates. Meanwhile, Tweety is released from Rainford, but is killed soon after while attempting an armed robbery. Later, Ramon informs Mick that Paco will be staying at Rainford pending transfer to another facility, and recommends that Mick avoid trouble if he wants to be released in six months. Paco arrives the next day and is assigned to Viking’s room, where the boys bond over their mutual hatred of Mick. When Mick confronts Paco, he accepts blame for Pacito’s death, but reminds Paco that he should have been “looking out” for his brother. Mick continues to maintain his composure while his fellow inmates lay odds on his expected battle with Paco. Angered by Viking’s constant harassment, Horowitz severely injures his nemesis with a time bomb placed inside a portable radio. Warden Bendix responds by placing Horowitz is solitary confinement for the remainder of his sentence. An inmate overhears the news that Paco is to be transferred the next day and word travels quickly through the dormitory. That night, Paco knocks Ramon unconscious and disconnects the alarm system, then attempts a sneak attack on Mick with a makeshift dagger, or “shank.” Mick lies in wait for Paco, and within seconds, the boys are engaged in a violent struggle over the weapon. The other inmates block all entrances to the dormitory as they gather around the fighters. Although Mick is stabbed in the leg, he overpowers Paco and grabs the shank. He holds the weapon over Paco as the inmates chant the word “kill.” Mick thrusts the shank into the floor and hobbles back to his room as tears run down his face.