Sheila Birling has become engaged to Gerald Croft and as a result, the Birling family have enjoyed a family dinner together. Mr Birling makes grand speeches giving his views on technology and industrial relations, emphasising his opinion that a man should only care about himself and his family and no one else. Their evening is suddenly interrupted by the arrival of a police inspector by the name of Goole who is making enquiries into the suicide of a young woman called Eva Smith.
The inspector has a photograph of the woman and from it Mr Birling admits that he once employed her in his factory but had sacked her over an industrial dispute over wages. Gerald Croft backs Mr Birling’s belief that he acted within reason. Sheila and her brother Eric react differently, feeling that their father was harsh in sacking her. However, upon seeing the photograph herself, Sheila realises that she also sacked the same woman from her job as a shop assistant.
During the course of Act I it becomes clear that the inspector has an uncanny knowledge about the family’s dealing with the girl. He then announces that the girl has in fact changed her name from Eva Smith to Daisy Renton. The reaction that this causes in Gerald makes it obvious that he knows the girl also. By the time we reach the end of the act the inspector is already suggesting that many people share the responsibility for the miserable existence of the young girl which prompted her to take her own life.
There is by now an evident tension between Sheila and Gerald that becomes heightened when he admits that he had had an affair with Daisy Renton in the spring of the previous year. Whilst feeling angry with Gerald for his involvement with the girl she does have a certain respect for his openness and honesty with his admission.
Mrs Birling attempts to intimidate the inspector and control the situation. Despite this, Sheila feels that it is foolish to try to hinder the inspector’s enquiries and this appears to be well founded. At the point when Eric is out of the room Mrs Birling is forced to admit that she also has an involvement with the girl. Two weeks earlier, she had refused the girl who had come to her seeking help. It is then revealed that the girl was pregnant and the suspicion now points at Eric as being the father of the unborn child.
Eric confesses that he was he who had got the girl pregnant. He also admits to having stolen money from his father’s firm in an attempt to support her. When he hears that his mother refused to help the girl he is horrified and blames her for both the death of the girl and of the unborn child. At this point, it becomes clear that nay family unity has now dissolved. The inspector has therefore done his job by showing each of them that they had a part to play in ruining the girl’s life.
He then goes on to make a speech about the consequence of social irresponsibility that is in direct contrast to the speeches made by Mr Birling at the start of the play. The inspector then leaves.
Gerald and Mr Birling begin to have doubts about the inspector’s identity and are gradually able to prove that the man was not a real police inspector. This then raises further doubts between them all about whether they have been talking about the same girl or indeed whether any girl had actually killed herself at all. Gerald telephones the infirmary who confirm that they have no record of any girl dying there that afternoon. Naturally there is a general feeling of relief upon hearing this.
Sheila and Eric still feel guilty about their action although they seem to have been changed by the recent events. The others, however, feel a greater sense of relief and their confidence in the rightness of their own actions is restored. At that point the telephone rings and Mr Birling answers it. It is the police calling to say that a young woman has just died on her way to the infirmary and that an inspector is on his way to make enquiries about her death.