The play begins with Alfieri, who serves as the play's narrator. Alfieri is a lawyer who was born in Italy and has great sympathy for his working-class clients. He tells of how certain cases make him think of Italy, even of ancient Rome. He introduces Eddie, and walks off the stage.
Eddie Carbone is a longshoreman in mid-20th century Red Hook. He lives with his wife Beatrice and his seventeen-year old niece Catherine. As the play opens he is talking sternly but affectionately to Catherine and warning her about the men who stare at her and how she needs to be careful about how she walks. She seems a little confused but loves her uncle and respects his opinions.
Eddie says he has news for Beatrice, and when his wife appears he tells her that her two cousins, Marco and his brother Rodolpho, have arrived from Italy. Since they will be here illegally they will be staying at the Carbone apartment. Beatrice is elated.
Catherine shares her own news, which is that she got a job as a stenographer; the pay is excellent and it was an honor to be asked to work there. Eddie does not approve: he is uncomfortable with her not being in school, and worries that the job is in a bad neighborhood. Eddie says that no one can be trusted, which also applies to the case of his wife's cousins, the immigrants—they must not tell anyone that they are here.
Eddie sadly smiles at Catherine as she heads out, wishing her the best. His emotion seems to irritate Beatrice and Eddie asks her why she is mad at him. She avoids answering.
Marco and Rodolpho arrive and the family welcomes them. Rodolpho’s bright blonde hair intrigues Catherine. Marco talks about how he wants to stay for a few years and work so he can provide for his wife and children, while Rodolpho, young and single, waxes poetic about how he wants to be a citizen and buy a motorcycle. He charms Beatrice and Catherine, especially when he begins to sing, but Eddie is skeptical and gruff.
Time passes and Catherine and Rodolpho begin to spend a lot of time together; this makes Eddie uncomfortable and he fights with his wife about it. She says Catherine is not a child anymore and if she wants to marry Rodolpho she can. She also wonders why Eddie will not sleep with her anymore. This makes him angry and he tells her to leave him alone about it.
Eddie’s problems with Rodolpho grow. His longshoremen friends laugh that Rodolpho is “funny,” and Eddie tells Catherine bluntly that he probably only wants to marry her so he can become a citizen. This hurts her greatly, and she bursts into tears and runs from him.
Upset, Beatrice tells Eddie he has got to leave Catherine alone. She goes upstairs to talk to Catherine, gently telling her that if she wants Eddie to treat her like an adult she needs to stop acting like a baby. She needs to be careful about what she wears and how she acts. Catherine is surprised by this and even seems a little afraid of Beatrice’s serious tone, but agrees.
Eddie visits Alfieri, telling him of his suspicions and asking if he has a legal recourse to stop Rodolpho from marrying Catherine. Alfieri patiently tells Eddie that there is nothing he can do unless he reports that they came illegally, but Eddie says he will do that. Eddie hints that Rodolpho is homosexual but Alfieri tells him he cannot prove anything. Eddie becomes angry and claims that he did everything for Catherine and now this guy is stealing her. Alfieri tries to tell him to be aware of his feelings for Catherine and let her go. After Eddie leaves Alfieri tells the audience that he could predict the end of this story by this point, and wonders why he felt powerless to intervene.
Tensions grow in the household. Catherine and Rodolpho continue to see each other, and one night Rodolpho boldly asks her to dance after dinner. Eddie glowers as he watches them but then jumps up and asks if he can teach Rodolpho how to box. The young man agrees but is nervous and does not want to hit Eddie. Eddie hits him but laughs it off as play. Marco sees what is going on and asks Eddie if he can lift a heavy chair. Eddie tries and fails, but Marco lifts it. His look of simmering anger and triumph frightens Eddie.
Catherine asks Rodolpho privately if he’d live in Italy with her when they get married because she is afraid of her uncle. He is frustrated by the question because he knows it is not coming from her. He tells her he loves her and wants to marry her but will not take a new wife from a rich country back to a poor country with no money. They can move away, though, and escape Eddie. Catherine is comforted and the two go upstairs and have sex.
Eddie enters the apartment and sees Catherine and Rodolpho after they’ve had sex. He flies into a rage and tells Rodolpho to get out. When Catherine says she will leave too he suddenly kisses her. Rodolpho protests that he cannot do that and Eddie kisses him as well in order to “prove” he is homosexual.
Later Eddie returns to Alfieri’s office but Alfieri tells him once more that there is nothing he can do. He starts to sense that Eddie might do something stupid and warns him, but when Eddie leaves, he does indeed call up immigration and reports the cousins.
At home Beatrice, weary and upset, chastises Eddie for kissing Rodolpho. Eddie is frustrated and tells her she needs to respect him more; she should also not bring up their bedroom issues anymore.
Beatrice tells him that Catherine is getting married next week because she is worried about Rodolpho getting picked up. She’d like to throw a party for them and hopes Eddie will participate. He is visibly distressed and decides to go for a walk. Before he can leave Catherine appears. He tries to convince her to wait but her mind is made up.
Knocks are heard at the door and two immigration officers enter the building. They begin their search in front of a grim Eddie and a frightened Beatrice and Catherine. Beatrice looks at Eddie, realization dawning on her face. When the brothers and two other immigrant relatives of a neighbor are brought downstairs, Catherine throws herself on Rodolpho, crying and proclaiming that he is a citizen.
The officers push her away and begin to take the men out. At one point Marco breaks away and spits in Eddie’s face, cursing his name and accusing him of killing his children. Eddie is incensed and screams after him as he is dragged away. The neighbors look upon him with disdain.
Alfieri meets with Rodolpho and Marco, Catherine also in attendance. He says Rodolpho has a chance if he marries Catherine but Marco will be deported anyway. He can bail out Marco now if he promises not to harm Eddie. Marco glowers in rage and says Eddie would be dead by now if he was back in Italy, but acquiesces.
Catherine and Rodolpho prepare to get married. Beatrice is planning on going to the wedding, but Eddie threatens her, saying she cannot come home if she goes. Distraught, she agrees to remain. Catherine is furious with her uncle.
Rodolpho arrives in a panic. He tells Eddie Marco is coming and to be careful. He also apologizes and tries to kiss Eddie’s hand, hoping that Marco will calm down if he knows he and Eddie are fine, but Eddie will have none of it. He yells that he needs his respect and he needs his name back.
Marco arrives. Neighbors begin to gather. Despite Beatrice and Catherine’s protestations, Eddie confronts Marco in a wild-eyed rage, claiming he needs his name. Marco moves toward him and Eddie pulls out a knife. They struggle and Marco turns the knife into Eddie, fatally wounding him.
Eddie dies in Beatrice’s arms. Alfieri, who was in the crowd, laments what happened but muses that Eddie is unique because he did not settle for a half life –he was wholly known and lived completely.