The curtain rises on Joe Keller reading the newspaper in his backyard in a small town soon after the end of World War II. A strong wind the night before has toppled an apple tree that was planted to honor Larry Keller, Joe and Kate’s son. A neighbor, Frank Lubey, visits and says that Kate has asked him to use Larry’s horoscope to determine whether November 25, the day Larry disappeared, was a “fortunate day.” Another neighbor, Dr. Jim Bayliss, engages in conversation with Joe, too.

A young woman named Ann (Annie) Deever arrived the night before and sleeps inside. Ann is staying in Larry’s room and used to be Larry’s girlfriend. Sue Bayliss and Lydia Lubey also appear and converse with their husbands. A boy named Bert pretends to be a police officer that Joe hires, and he imagines a jail in Joe’s basement.

Chris Keller, Joe and Kate’s other son, enters and tells Joe that he saw Kate in the yard the night before when the tree fell and that she ran into the house, crying. They agree that Kate clings to the hope that Larry will return, but they both acknowledge that it’s impossible. Chris tells Joe that he has invited Ann to visit because they are in love and intend to marry. When Kate appears, she describes a vision she had of Larry flying his aircraft over their house, calling for his mama. When Kate admits that she can’t handle the reality of Larry’s death, Joe and Chris agree that they will tell Kate about the impending wedding that evening at dinner after a few drinks.

When Ann joins them in the yard, Jim asks about her father in prison. It is revealed that Ann’s father, Steve Deever, and Joe were business partners. Three years earlier, their factory built aircraft engines for the Air Force. When it was discovered that someone had knowingly shipped cracked engines that resulted in the deaths of twenty-one American pilots, Steve Deever was found guilty, but Joe was exonerated because he wasn’t in the plant the day the faulty engines were shipped. The entire play revolves around this past event. Ann accepts Chris’s marriage proposal and listens to Chris’s own war story. At the end of Act One, Ann gets a phone call from her brother, George, who has just visited Steve in prison. George will arrive soon to talk to Ann, but no one knows why.

Chris saws the broken apple tree in the beginning of Act Two. Sue and Ann discuss marriage, and Sue criticizes Chris’s idealism. She suggests that everyone knows that Joe was guilty, too. Jim has gone to pick up George from the train station and returns, warning Joe that George is angry and means to start trouble. George has come to confront Joe and to bring Ann home. When George appears, he and Chris talk about work. George is wearing his father’s hat and confesses to Ann that they have treated Steve poorly by not communicating with him and not believing his story of what really happened at the factory. Steve told his son the truth, that Joe gave the order to ship the cracked engines and then faked being sick so as not to come to the factory that day. George wants to confront Joe directly, but Ann talks him into waiting. Lydia is happy to see George because they were once romantically involved.

When Joe appears, he inquires about Steve and offers him a job at the plant when he is released from prison, but George makes it clear that Steve hates Joe and anyone else who profited from the war. When Kate claims that Joe hasn’t been sick in fifteen years, George immediately recognizes the lie about having the flu, which was his excuse for not being at work the day of the incident. Joe tries to correct Kate’s slip, but it’s too late. Suddenly, Frank appears to tell them that Larry’s horoscope reveals that he might still be alive, which only reinforces Kate’s delusion. Chris calls the idea insane, but Kate holds fast, and George wants to leave with Ann. In a moment of clarity, Kate reveals to her son, Chris, that she knows about Joe’s role in the munitions shipment. Stunned by the truth, Chris explodes at his father in fury.

Act Three takes place in the dead of night. Chris has driven away, and Kate sits on the porch alone. Jim appears and reassures her that Chris will return. He also tells Kate that he’s known all along about Joe’s guilt. Kate tries to explain to Joe that Chris believes in more than money and family, a value that Joe cannot agree with. Joe claims that he’d kill himself if there was something more important than family. Ann appears with a letter from Larry, a piece of evidence that she’s been holding back from the family. Ann wants Kate to free Chris from the lie about Larry, but since Kate refuses, she must share the truth. Chris appears and apologizes to Ann for being a coward. He can no longer be in Joe’s business and will find a new life in Cleveland. His idealism has turned into cynicism.

When Joe reappears, another fight ensues. Joe tells Chris to throw away the family money if he considers it dirty. Chris admits that he worshiped Joe blindly and now sees the world for what it is. Ann chooses to share Larry’s letter, which contains the revelation that finally breaks this family in half. In the letter, Larry confesses to committing suicide in response to Joe’s crime. Joe responds to this news by quietly claiming that he now understands and goes inside to shoot himself. The play ends with Kate holding Chris, trying to comfort him, and telling him that he must go on living.