Amy and Jim Preston, a middle-aged married couple, live with their teenage son Brian in a cramped and untidy London council flat. Amy is kind and loving but very disorganised, hence the household's chaotic state. Unbeknown to Amy, Jim is having an affair with a pretty young secretary from work, Georgie Barlow. He tells Amy he has to go into work on Sunday to put in some extra hours when he is actually planning to meet his mistress. Georgie wants Jim to leave his wife and start afresh with her. Jim wants to do this too but finds it impossible to break the bad news to Amy. When he arrives home on Sunday evening, he and Amy go to the pub together, but when he tries to broach the subject, he is interrupted by the arrival of their neighbours Hilda and Harold.

The next day at work, Georgie expresses her frustration about Jim's lack of decisiveness and threatens to call off the affair and get a job somewhere else. Jim manages to talk her round and they go for a quick drink together. Jim promises he will tell Amy he wants a divorce. When Jim gets home that evening, he finds that Amy has attempted to organise the flat and has cooked him a special meal. They get into a slight argument over a pile of undone ironing and Jim storms off to the bedroom, followed by his wife. It is here that he finally blurts out that he wants a divorce. Amy is completely surprised, thinking that they have been a very happy couple. Jim begins to explain about his relationship with Georgie, but is interrupted by the arrival home of Brian, with his girlfriend Christine. Jim pretends that everything is normal but Amy cannot go through with the pretence and disappears off the bathroom, where she bursts into tears.

The next morning, Amy rises very early and does all the housework, hoping that the problems in her marriage are only superficial and can be solved by being a more efficient housewife. Jim hurries off to work. Amy borrows some money from Brian and pawns her engagement ring to raise some extra cash. Her plan is to invite Jim and Georgie back to the flat that evening so the three of them can discuss what they plan to do about the situation, and Amy wants to present herself in the best possible light. She goes to the hairdressers to get her hair done (usually just tied back scruffily) and buys a bottle of whisky. But she gets caught in the rain and her hairdo is ruined, and to make matter worse, her best dress rips when she puts it on. Hilda pops round and when Amy tells her about Jim's affair and the meeting planned for that night, Hilda suggests they drink a bit of the whisky for 'Dutch courage'. Amy soon feels quite tipsy but carries on preparing for Jim and Georgie's arrival. It is only when the lyrics of the song she is absent-mindedly humming remind her of her predicament that she pauses and becomes upset. The table she is sitting at collapses beneath her. Brian arrives home and finds his mother in a distraught state and puts her to bed. Then Jim and Georgie arrive. Brian is very angry at his father and at Georgie for destroying the family unit.

Amy recovers from her drunken stupor and goes to the living room to confront her husband and his mistress. She criticises Georgie for coldly stealing another woman's husband and reveals that she had a child that died in infancy. She loses her patience with Jim and Georgie and tells them to leave immediately. They go, but halfway down the street Jim realises he cannot go through with abandoning his wife and son. He goes back to the flat and is tentatively welcomed home. Brian asks his dad to look over some notes for a speech he is making and Amy repairs to the kitchen to make a pot of tea.