Mark Thackeray (Sidney Poitier), an unemployed man, applies for an engineering job but it will be a long time before a decision is made. He also applies for, and is awarded, a teaching position at the North Quay Secondary School in the tough East End of London. He comes from British Guiana via California.
Thackeray learns from the staff of North Quay that most of the pupils have been rejected from other schools, and their antics drove their last teacher to resign. The pupils live up to their reputation. Led by Bert Denham (Christian Roberts) and Pamela Dare (Judy Geeson), their antics progress from disruptive behaviour to distasteful pranks. Thackeray retains his calm manner but a turning point comes one morning when one of the female pupils acts disrespectfully. He loses his temper, then informs them that from now on they will be treated as adults and allowed to discuss issues of their own choosing for the remainder of the term. Future classes discuss what the students can expect as adults, such as how to fill out resumes.
Thackeray wins the class over, except for Denham, who continues to bait him. Thackeray suggests a class outing to a museum, which turns out to be a success. He loses some of this new-found support when he defuses a potentially violent situation between Potter (Chris Chittell) and a gym teacher, Mr Bell. In class, he demands that Potter apologise directly to Bell for the incident even if he believes Bell was wrong. The group refuse to invite Thackeray to the class dance, and when 'Seales' (Anthony Villaroel) mother dies, the class takes up a collection for a wreath but refuses to accept Thackeray's donation. At this point, the headmaster advises him that he feels "the adult approach" has failed; future class outings are cancelled, and Thackeray is to take over the boys' gym classes. Meanwhile, Thackeray receives an engineer job offer in the mail.
He starts to win the pupils back after he beats Denham in a boxing match, but tells him that he has genuine boxing ability and suggests that Denham teach boxing to the younger pupils next year. Denham expresses his admiration for Thackeray to his fellow pupils, Thackeray wins back their respect and is invited to the class dance.
At the dance Barbara Pegg (Lulu) announces a "ladies choice" dance and Pamela (Judy Geeson) chooses Thackeray as her dance partner. While Miss Pegg (Lulu) sings the film theme song, the class then presents Thackeray (Poitier) with a gift and he is too moved for words and retires to his classroom.
Two youths rush into the classroom, and upon seeing Thackeray they begin mocking his gift and joking that they will be in his class next year. Thackeray realises that he has a job to do and he tears up the job offer letter, signifying that he is going to stay on at the school. He realises how affectionate he feels towards the children and understands he can never part from them.
Who is gift is mocked by the two youths in the classroom?
Thackeray