There is a light-hearted atmosphere at dinner as the Birling family celebrate the engagement of Sheila and Gerald Croft. The dinner party consists of Arthur, Sybil, Sheila, Eric and Gerald. Edna - the Birling family's parlour maid - is also in and out of the scene.

There are hints of drama and tension. Mr Birling is keen to impress his soon-to-be son-in-law. Gerald's father owns the company Crofts Limited, a direct competitor to Birling and Company. Arthur believes that the impending marriage will help bring the two companies together. He emphasises that their competition has so far been civil, and that the Crofts' is the larger company and the older, more distinguished family.

The Crofts are not at the dinner party to celebrate their son's engagement, as they are supposedly abroad. Mr Birling believes that Lady Croft was hopeful that her son would marry someone of a higher status than Sheila.

Sheila teases Gerald about his distant behaviour during the previous summer. In response, Gerald explains he was busy with work. He soon presents his fiancé with a ring. Sheila is delighted and shows it off to her family.

Eric seems nervous and on edge. Sheila accuses him of being 'squiffy'.

Arthur is in good spirits and makes a number of speeches. He declares that he is soon expecting a knighthood after previously being Lord Mayor. He jokingly assures his family that he is certain of this honour, as long as they avoid a scandal.

Arthur then explains that a man is responsible for looking after himself and his own family, paying no attention to the wider community. As he is telling them this, the door bell rings.

Edna answers the door to Inspector Goole. Although Mr Birling tries to take control, the Inspector dominates the interaction by announcing that he has come to investigate the suicide of Eva Smith, a young working-class girl who died that afternoon at ‘the infirmary’. She had killed herself after drinking disinfectant.

Mr Birling recognises the girl from a photograph and declares that he fired her from his factory. His reasoning was that she was one of the ring-leaders of a strike asking for higher wages. Birling does not present any guilt or remorse; he cannot see that he has any responsibility for the following sequence of events.

The Inspector then moves on to question Sheila. She becomes distressed as she discovers more about the Eva's tragic story and the description of her brutal suicide. Sheila starts to appear concerned when the Inspector reveals that Eva's next job was at a big shop called Milwards. He explains that she was sacked after a customer complained about her. When she too is shown a photograph of the girl, Sheila becomes inconsolable and admits that it was her fault that Eva was sacked. She is horrified by what she did and feels guilty.

Finally, Goole then reveals that Eva went on to charge her name to Daisy Renton. Gerald's immediate reaction suggests that he too was familiar with the girl in question.

Initially, Gerald tries to deny any involvement and encourages Sheila to leave the room. However, he soon admits that he knew Daisy Renton. He explains that he met her in ‘the Palace Bar’, where she was being harassed by lecherous Alderman Meggarty - a council member infamous for being a 'sot' and womaniser. Upon discovering Meggarty's forceful advances, he rescues Daisy by pretending she is his girlfriend.

After finding out that Daisy has nowhere to live and is penniless, he buys her dinner and lets her stay in the flat of a friend. She soon becomes Gerald's mistress and begins to fall deeper in love with him. The Inspector knows about her feelings as she regularly kept a diary. Gerald decides they should end the relationship. Daisy decides to move out of the rooms. He gave her some money to fund her survival for a few months. Sheila is clearly upset and disappointed; it was during this affair that Gerald had told his fiancé that he was busy at work.

Soon after, Inspector Goole then moves onto question Mrs Birling. She is convinced that she has no connection with the girl. After showing her a photograph of Eva and some encouragement from Sheila, Sybil has to admit that she had seen the girl two weeks previously.

The girl - now pregnant - had come to ask for financial support from the Brumley Women's Charity Organisation where Mrs Birling was chairwoman. Sybil had denied the girl any support. She claims that Eva initially lied to the committee, telling them that her name was 'Mrs. Birling' and that her husband had abandoned her. When pressed, she admitted that she was pregnant, and that the father had been stealing money to support her and the baby. She was desperate for the committee's assistance so she would not have to rely on stolen money.

Sybil now lacks any feelings of guilt or remorse. In fact, she is believes she did her duty, and blames the man who got Eva pregnant. She declares that the unborn baby's father should be publicly shamed for his poor behaviour.

Sheila desperately urges her mother to stop talking, as she and the audience have realised at this point that Eric is involved. Just as Sybil blames the father of the baby, Eric re-enters the room.

During the final act, the relationships in the family begin to break down. The Inspector interrupts the family undertaking a tense argument. Goole questions Eric about his connection with the girl.

Eric explains that he met her in the same place as Gerald, and admits that he too had a relationship with her. Sheila notes that her brother is an alcoholic, and he admits that he forced himself on Eva whilst in a drunken state. Soon afterwards, she discovered that she was expecting a baby.

Eric offered to marry her, but she rejected him as she knew he did not love her. He then stole money from his father's office to try and financially support her. Mr Birling abruptly reacts, showing that he is more concerned about his reputation and avoiding a scandal.

The Inspector delivers a powerful speech about each character's contribution to the girl's suicide. He warns what will happen if people do not soon realise that we are all responsible for each other. He then leaves the Birling house.

The family begin to question the Inspector's identity. Gerald has discovered that there is no Inspector Goole in the police force. Arthur then phones the chief constable for further confirmation. When they then telephone the infirmary, they are informed that there hasn't been a suicide case for months. Mr Birling is clearly thrilled as he now thinks that they are relieved of any responsibility. Sybil and Gerald are also relieved of any guilt. Sheila and Eric, on the other hand, still feel guilty and insist that nothing has changed - each of them still committed the acts that the Inspector had accused them of. At this point, the telephone rings.

Mr Birling answers the call. As the tension builds, he tells the family that it was the police on the line: An inspector is on his way to ask questions about the suicide of a young girl...