Danny is an English teacher in a South London comprehensive. When three youths break into his class and threaten Patrick, one of his pupils, Danny intervenes and is himself threatened with a knife before the youths leave. Shaken, Danny confonts Patrick and demands that he tell him the name of the ringleader.

Danny discovers that the boy, Stefan, lives at the care home known as Number 66, where he himself spent much of his youth. He visits the home and is welcomed by his former foster mother Agnes Miller, who runs the home. He confronts Stefan and is shocked and infuriated by the boy's hostile attitude.

Danny becomes increasingly obsessed with Stefan and visits the home frequently. Eventually, he resigns his teaching job and takes a job at the home, but his hot-headed and sometimes confrontational approach do not go down well with some of Number 66's troubled kids, particularly Stefan. At the same time, Danny begins a tentative affair with Kay, another worker at the home.

Meanwhile, Stefan has fallen under the spell of Bonaface, a local gangster, and is being drawn deeper into a life of petty crime.

At a New Year's Eve party, one of the girls at Number 66, Annalise, overdoses on solvents. Her friend, Melody, is persuaded to leave her by boyfriend Shinehead, and Annalise dies in hospital. Later, Stefan blames Shinehead and vows revenge.

Stefan, on the run from the police, leaves Number 66 to hide out at the home of Rosa, Annalise's mother, a drug addict. Some days later, Danny comes upon a confrontation between Stefan and Shinehead. When Shinehead pulls a knife on Stefan, Danny intervenes and Shinehead leaves. Back at Number 66, Stefan fights with best friend Paul over a stolen jacket. He runs off and Danny follows him and confronts him with Boniface. Stefan is defiant and Danny leaves. But Stefan follows him back to Number 66, furious. In his anger he ransacks the kitchen, throwing anything he can find at Danny until finally he breaks down in tears. Danny comforts him.

Later, Stefan, who seems to have made his peace with Danny, is out in an amusement arcade with Paul and another friend when they are confronted by Shinehead and his gang. Stefan is stabbed repeatedly by Shinehead.

At Stefan's funeral the preacher, Mister, begs the young people to value themselves and their lives.