Notting Hill, London 1959. A group of children prepare a huge bonfire in the street for Guy Fawkes night.

Kathie Palmer, a 24-year-old school teacher, has fallen in love with black colleague Peter Lincoln. Thus far, Kathie has managed to keep her relationship with Peter quiet, but a particularly gossipy neighbour spots the couple on their way home and drops a hint to Kathie's mother, Nell Palmer.

Kathie's father, Jacko Palmer, the shop steward for the local factory, wants to promote fellow black worker, Gabriel Gomez, to the level of foreman. He knows he will face opposition to this because some workers have expressed a refusal to take orders from a 'spade'. Gomez is already temporarily promoted to that position and a few white workers have formed into a group of dissenters who intend to vote against the move.

After hearing that Kathie has been seen with a black man, Nell's mood and demeanour changes. She is deeply concerned about the colour of Kathie's boyfriend. Several times during the course of the evening Nell tries to ask Kathie about the man she has been seen with. Kathie deliberately avoids the question.

In an unguarded moment Kathie lets slip to her father that she is seeing someone and that it is quite serious. Jacko is elated and immediately jumps the gun with talk of marriage. Gomez has an argument with his pregnant white wife Judy, who, in an outburst, calls him an animal. Later, Gomez refuses to go to the union branch meeting at which his promotion will be discussed, but, after another angry exchange with his wife, he is persuaded to go.

At the meeting there is much opposition to Gomez's promotion but a rousing speech from Jacko in which he cites equality as a founding principal of trade unionism, completely changes the general consensus and Gomez's promotion is ratified by a vote.

In the streets, a racially mixed group of children and families light the bonfire and let off fireworks. Three white yobs from a different area of town try to disrupt the festivities by throwing bangers at the crowd. They then set upon a lone black passer-by, who is then defended by three burly white men. The yobs move away vowing to come back with a larger gang.

Back at home, to his dismay, Jacko learns the truth about Kathie's boyfriend. Kathie is confronted by her parents and admits that her boyfriend is black. Nell is now enraged and on the verge of hysteria. She issues a long caustic volley of racial abuse at Kathie who runs out of the house. Nell calls after her saying that she will never accept her black boyfriend. Jacko is so shocked and dismayed at his wife's language that he is momentarily struck dumb. Expressing surprise at the depth of his wife's prejudice he goes out after Kathie.

Jacko goes to Peter's flat where he finds Kathie. He asks whether they love each other enough to cope with the level of prejudice they will encounter if they get married. The couple affirm their love and insist they are prepared for anything. He agrees to support them and persuades them to return home with him.

In the street, the three yobs return with a large gang. A gang of black men gather to defend their area. A large fight breaks out in the streets. Gomez tries unsuccessfully to stop the fight. Jacko and Peter get caught in the mêlée as they make their way home. Gomez is pushed into the bonfire and is badly burned. The police arrive and the yobs run off. An ambulance arrives and takes Gomez to hospital.

Back, home after a great deal of effort, Jacko persuades Nell to confront Peter, with a view to accepting him.