Alfieri, our friendly neighborhood lawyer and narrator, kicks the play off with a monologue. He tells us we're in Red Hook, a slum in Brooklyn. Alfieri pops up in between scenes to get his narration on, letting us know a little more about the characters and the themes in the play that we're supposed to giving our attention. At the end of his first monologue, he introduces us to protagonist extraordinaire, Eddie Carbone, a longshoreman who's spent his whole life working the docks of Red Hook.
Soon we meet Eddie's family. He has a lovely young niece, Catherine, and a wife Beatrice – a mouthy housewife with a heart of gold. Catherine has just been offered a job as a stenographer (kind of like a secretary) at a plumbing company. Eddie, king of overprotective father figures, is hesitant to let her take it, even though it won't interfere with her schooling. Eventually he chills out about it and gives the OK. We also learn that Beatrice has a couple of cousins who will soon arrive from Sicily, Italy. They're being smuggled into the country illegally. They plan to live with the Carbones while working on the docks.
The cousins, Marco and Rodolpho, soon show up, and everybody gets acquainted. Marco is a big, traditionally masculine kind of guy. He's come to America to send money back to his starving tuberculosis-ridden family. Marco wants to go back to Sicily after a few years. His younger brother, Rodolpho, is a fun-loving and talkative. He plans to stay in America forever. Rodolpho decides to show off his singing skills, regaling everybody with a lovely rendition of the song, "Paper Doll." Catherine is wowed – far too wowed for Eddie's taste.
Before too long, Catherine and Rodolpho are dating. Eddie thinks this is the worst thing that's happened in the history of the Earth. He becomes obsessed with breaking up the happy couple. First he tells Catherine that Rodolpho is trying to marry her so that he can get his American citizenship. But that doesn't work. Next, Eddie goes to Alfieri, the lawyer, to see if there's any legal action he can take. Eddie tells Alfieri, in a roundabout way, that he thinks Rodolpho is gay. The longshoreman's main evidence is that Rodolpho sings, dances, sews, cooks, and has blonde hair. Alfieri is unconvinced, and anyway there's nothing the law can do to stop the relationship – unless, of course, Eddie calls Immigration on the cousins. That would be highly unadvisable, though, because the whole community would hate him for such a betrayal. It's becoming pretty apparent by this point that Eddie's over protectiveness of Catherine may stem from more than fatherly concern. He seems to have repressed incestuous feelings for his young niece.
Tension continues to build until Eddie comes home drunk and finds the young couple alone in the apartment in post make-out mode. Eddie flips out, grabs Catherine, and kisses her on the lips. When Rodolpho tries to defend her, Eddie beats him up and kisses him, too. At this point, Eddie heads back to Alfieri, because he's sure, for some odd reason, that by kissing Rodolpho he's proven that the young man is gay. This would, of course, prove that the wicked Sicilian is only using Catherine. Alfieri once more tells Eddie that there's nothing the law can do about it. Eddie, frustrated and desperate, calls Immigration on Marco and Rodolpho.
This act of betrayal turns into a real disaster. Not only do Marco and Rodolpho get arrested, but a couple of other immigrants do as well. As he's being dragged into the street, Marco spits in Eddie's face and accuses him in front of the whole neighborhood. Eddie's reputation is destroyed.
The last events of the play fire in quick succession. Alfieri bails out Marco and Rodolpho. The lawyer makes Marco promise not to take revenge on Eddie. Catherine and Rodolpho plan to get married immediately. Eddie forbids Beatrice to go to the wedding. Marco ignores his promise and shows up outside, yelling for Eddie to come down and face him. Beatrice, trying desperately to stop Eddie, tells him it's not his "name" (his reputation) he really wants, it's Catherine. Eddie can't even begin to deal with that idea and rushes down to face Marco. He pulls a knife on the Italian. Marco twists Eddie's arm around such that the longshoreman's own knife impales him. Eddie dies in Beatrice's arms.
We end the play with another monologue by Alfieri, where he tells us that he mourns Eddie, even though the longshoreman was totally misguided.