The play opens with the lawyer Alfieri, who sets the scene. He talks about justice and how, sometimes, justice is dealt with outside the law. He says he has a timeless story to tell - one that ran a "bloody course" he was powerless to prevent - and introduces its hero, Eddie Carbone.
One day Eddie arrives home from the dockyard where he works with some news. He announces that Beatrice's two cousins from Italy have reached New York and they will arrive at the family's home at 10 o'clock that night. It is obvious that the family has often discussed the visit before - Beatrice is anxious that she hasn't completed all the preparations in the house she had intended to welcome them, and Eddie reminds Beatrice not to be so kind to the cousins that he will be turned out of his own bed for them. Yet he then claims it is an honour for him to be able to help them.
Act 1 - 2
Catherine also has some news: she tells Eddie that she has been picked out of all the girls in her typing class to be offered a well-paid job at a big plumbing company. She is excited at the prospect, but Eddie is worried: he doesn't want her mixing with strangers, wants her to finish her education and is concerned for her safety. Beatrice takes Catherine's side, however, so in the end Eddie relents and allows Catherine to take the job.
Because the cousins are illegal immigrants, Eddie reminds Beatrice and Catherine not to mention them outside the house. To reinforce the danger, Eddie tells the story of Vinny Bolzano, who let on to the Immigration authorities that his family were hiding an uncle - and the bloody consequences.
Act 1 - 3
The cousins, Marco and Rodolpho, arrive and are warmly welcomed. The quiet, polite Marco reassures Eddie that they will not outstay their welcome and talks about his family left behind in Sicily, desperate for the cash that he will be able to send them once he starts work. He hopes to go home in about six years. The cheerful Rodolpho describes what it is like living in a poor peasant village: unlike his brother, he wants to stay in America. Rodolpho shows off his voice by singing 'Paper Doll', to Catherine's delight. Eddie puts a stop to the music because he doesn't want suspicions raised in the neighbourhood, but we also sense Eddie's dislike of Rodolpho - his face is "puffed with trouble."
Act 1 - 4
A few weeks later, Eddie and Beatrice sit waiting for Catherine and Rodolpho to come home from the cinema. It is clear that Rodolpho and Catherine have fallen in love. Eddie's hostility towards Rodolpho is now more open and he is anxious - Beatrice jokes that he must to jealous of Rodolpho. She admires Rodolpho and hope that he and Catherine will marry, but Eddie is appalled by this idea. This conversation leads Beatrice to ask Eddie about the state of their own marriage: they have not made love for months. Eddie refuses to discuss it.
When Catherine and Rodolpho finally return, Eddie asks to speak to Catherine alone. He repeats, wistfully, that she has grown up without his realising it. When she admits to liking Rodolpho, Eddie tells her that Rodolpho is only using her and that he just wants to marry an American to gain US citizenship. Catherine is very upset. She admits privately to Beatrice that she loves Rodolpho and wants to marry him, but that she doesn't want to hurt Eddie. Beatrice advises her to be more independent and grown up, and less intimate with Eddie in the house.
Act 1 - 5
Eddie goes to see Alfieri, wanting the law to step in to stop Catherine marrying Rodolpho. He claims that Rodolpho is only doing it to gain a US passport, and that Rodolpho is homosexual. Eddie is amazed when Alfieri explains that no law can prevent the marriage. Alfieri hints that perhaps Eddie loves Catherine too much (over and beyond the caring, uncle-niece love which could be expected), to which Eddie reacts angrily.
There is tension in the air when we next see Eddie, Beatrice, Catherine, Marco and Rodolpho at home together. Eddie makes barbed comments, implying that Rodolpho is too friendly with Catherine and too casual with his money. He pretends to admire the fact that Rodolpho can cook, sew and sing, before adding that it is wrong for someone with those skills to work at the docks. He offers to treat Rodolpho and Marco to a night watching a prize-fight and teaches Rodolpho to box. This is clearly just an excuse to punch Rodolpho, but Rodolpho takes it good-humouredly. Catherine shows that she is more interested in Rodolpho's safety than Eddie's. Marco shows off his own strength to Eddie by lifting a chair by its leg with one hand - a feat that Eddie cannot match.
It is nearly Christmas. Catherine and Rodolpho are alone in the apartment for the first time. Catherine is sombre. She asks Rodolpho if they could live in Italy when they are married, but he claims it would be ridiculous to go back to such poverty. He does reassure her that he is not going to marry her just to gain US citizenship, however. She says that she doesn't want to hurt Eddie. When he has comforted her, they go into the bedroom. Eddie returns, drunk, and is aghast to see Rodolpho follow Catherine out of the bedroom. He tells Rodolpho to leave immediately; Catherine says that she will go too, but Eddie grabs her and kisses her. When Rodolpho protests, saying Catherine is going to be his wife, Eddie kisses him too. The men fight, "like animals".
Act 2 - 2
Four days later, Eddie returns to Alfieri and tells him what happened. Marco has not been told of the fight. Alfieri reiterates that there is nothing Eddie or the law can do to prevent the wedding. He advises Eddie to let the couple marry, warning him that there could be awful consequences if he didn't. Yet Eddie ignores Alfieri's words and telephones the Immigration Bureau, anonymously, to betray the cousins. When Eddie returns home, he finds that Marco and Rodolpho have moved upstairs to a neighbour's apartment. There is a tense conversation with Beatrice - she is very angry with him. Beatrice tells Eddie that Catherine and Rodolpho are going to get married next week, ironically because Catherine is afraid that the authorities will catch up with the brothers. She tries to get Eddie - who has tears in his eyes - to agree to come to the wedding and, when Catherine comes in, Beatrice encourages Catherine to ask Eddie herself. Catherine refuses to listen to Eddie's suggestion that it is not too late for her to meet other boys - his last-ditch attempt to prevent the wedding.
Act 2 - 3
When Eddie discovers that Marco and Rodolpho are lodged with two other illegal immigrants upstairs, he becomes concerned and warns that they will be less safe from the authorities there. He is obviously regretting the call he made to the Immigration Bureau, but it is too late - two officers arrive. It is clear that Beatrice and Catherine immediately suspect that Eddie was the informer. As the officers lead Marco, Rodolpho and the two other immigrants away, Catherine pleads with the men to spare Rodolpho and Marco spits in Eddie's face. Eddie shouts out that he'll kill Marco; Marco retorts that Eddie has stolen food from his children. Eddie protests that he is innocent, but all the neighbours turn away from him. The honour of both Eddie and Marco is now at stake. We next see Marco and Rodolpho and Catherine with Alfieri's in the reception room of the prison: Alfieri needs a promise from Marco that he will not kill Eddie as a condition of bail. Marco is reluctant, feeling that Eddie should be punished, but agrees.
Act 2 - 4
It is the day of the wedding. Beatrice gets dressed in her best clothes, but Eddie tells her that if she goes, he won't let her back into the house. Catherine is angry, calling Eddie a rat. When Rodolpho arrives to take Catherine to the church, he says that Marco is at the church, praying. Eddie's fury rises: he wants to get even with Marco, for ruining his good name in the neighbourhood. Beatrice tries to calm him, telling him that the reason he is angry is because he is about to lose Catherine for ever - but this truth fires Eddie up even more. Marco arrives, calling Eddie's name. Eddie goes to meet him in the street and demands a public apology. Instead, Marco calls him an "animal". Eddie draws a knife but Marco is able to grip Eddie's wrist and turn the knife on Eddie himself. Eddie dies in Beatrice's arms. Alfieri closes the play, commenting on how useless Eddie's death was, and on how much he admired him for allowing himself to be"wholly known."