The first act of All My Sons takes place in the backyard of the Keller home early one Sunday morning in August. The yard is both secluded and comfortable, and its contents suggest a normal upper-middle-class American home: a small trellised arbor, some garden chairs, a table, a garbage pail, and a wire leaf-burner. A slender apple tree, cut in half by a violent wind, is the only other noticeable piece of stage property.
As the play begins, Joe Keller is bemusedly reading the classified adds in the Sunday paper. Jim Bayliss, his physician neighbor, has joined him. They are soon joined by another neighbor, Frank Lubey. Noticing the tree, Frank remembers that this is the month of Larry’s birthday. Larry was Joe’s eldest son and, as a pilot in the war, was shot down three years ago. Because his body was never recovered, Kate, his mother, hysterically clings to the belief that he is still alive. Joe informs the two men that Ann, who had been Larry’s girlfriend, has returned to the neighborhood and is sleeping in the guest room.
After Frank and Jim leave, Chris, Joe’s younger son, enters. Joe wonders if Kate has seen the damaged tree, but his musing is cut short by the excited entrance of Bert, a young boy. During a comic scene, it becomes clear that Joe has “deputized” Bert to monitor the behavior of the neighborhood children. Further, he has shown Bert a gun and convinced the impressionable young boy that the basement of the house is, in reality, a jail. The boy leaves, and Chris confronts his father. First, he argues that they should not have allowed his mother’s romantic belief that Larry is still alive to continue for so long. Second, he announces that he plans to marry Ann, that he is tired of working in his father’s business, and that if his mother refuses to accept his marriage and Larry’s death he will leave. Joe promises to help, but their conversation is interrupted by the arrival of Kate.
Kate, who suspects that Ann’s arrival has some deeper significance, says that she has seen Larry in a dream. She points to the felled tree as proof that her son is still alive. Chris exits into the house. Kate immediately turns on Joe, demanding to know why Ann has arrived. Further, she threatens that if Larry fails to come home she will kill herself. She is interrupted, however, when Chris comes into the yard with Ann.
In the tense scene that follows, Ann flatly dismisses Kate’s belief that Larry is still alive. Further, she refuses to forgive her imprisoned father: Her father, Joe’s business partner, has been convicted of knowingly supplying cracked cylinder heads to the Army Air Force. As a result, twenty-one planes crashed, killing twenty-one pilots. Joe, who was found innocent of the same charge, defends her father as a “little man” caught in a situation beyond his control. After his parents have left, Chris and Ann confess their love for each other. She asks him why he waited so long to reveal his love; Chris replies that, after the war, he could find no meaning in life, feeling guilty that he was alive when so many had died. Their intimacy is broken by the news that Ann’s brother George is on the phone. George, a lawyer, has seen his father in prison and wants to talk to Ann immediately. As Chris and Ann leave, Joe and Kate nervously await the arrival of George.
Act 2 begins in twilight. Chris is sawing the apple tree when his mother enters from the house. Kate tells Chris that she is afraid, and that she wants Ann to leave with George when he arrives. Ann’s arrival ends their conversation, and Kate exits. Chris promises to tell Kate about their plans to marry, then he, too, leaves. Ann is joined by Sue, Jim’s wife. Their private talk quickly centers on marriage, and Sue harshly demands that once Ann and Chris are married they move away. Startled, Ann defends Chris’s idealism. Sue, however, retorts that Chris’s idealism has affected her husband. Under Chris’s spell, Jim has come to see his life as shallow, believing that instead of being a physician he should be conducting medical research. Sue suggests that it is easy to be an idealist when one can live in comfort, as Chris lives a world of financial well-being secured by his father’s corrupt business practices.
Joe enters the yard and suddenly announces that he will find jobs for both George and his father. Although Chris and Ann reject the idea of Joe’s helping his former partner, Joe defends his plan by emotionally shouting “a father is a father!” He retreats into the house, fearing that he has perhaps revealed too much. Jim arrives, having met George at the station; he tells Chris not to let him enter the house, suggesting that George’s plan is to take Ann away and to expose an old secret. Chris, unafraid of the past, tells Jim not to worry and goes forward to meet George.
George accuses the absent Joe of destroying his family and asks Ann not to marry Chris. He outlines his meeting with his father, saying that he now believes his father’s plea that Joe knew about the defects in the cylinder heads but ordered him to weld over the cracks and ship them out. Chris replies that he still believes in Joe’s innocence. The entrances of Kate and neighbor Lydia reduce the tension, and George seems to be slowly emerging from his explosive and dark mood. Joe finally joins the assembled group and tries to convince George that his father has always been unable to see his own faults. For a brief moment, the group is relaxed, and their laughter suggests a more promising future. The calm is abruptly destroyed, however, when Kate says that Joe has never been sick in fifteen years. This admission is a crucial mistake: Joe always claimed that he had pneumonia the day the cracked cylinder heads were manufactured. George begins to question Joe. George then tries to make Ann see the truth, Kate asks Ann to leave, and Chris attempts to shock his mother into accepting Larry’s death. Suddenly, Kate tells Chris that if he has lost all hope for his brother then he must also give up hope for his own father. Unable to answer her, Joe confesses his guilt to Chris. Chris, lost and crying, stumbles offstage as his father tries to call him back.
Act 3 takes place at two o’clock the following morning. Alone on the stage, Kate is rocking ceaselessly in a chair, waiting for Chris to return. Jim enters, and after admitting that he had also known that Joe was guilty, tells her that Chris will return, that like everyone else, he will make a compromise with his own impossible standard of honesty and return home. As he leaves, Joe enters, wondering if Ann— who has stayed in her room since Chris’s departure—knows what has happened. Joe talks about his need for Chris’s forgiveness, threatening suicide if Chris can not forgive him. Quietly, Ann enters and confronts Kate.
As Ann shows Kate a letter from Larry, Chris returns. In an emotional confrontation with his father, Chris refuses to forgive him. Chris turns away from Joe, and Ann takes the letter from Kate and gives it to Chris. He reads it aloud. Written moments before Larry’s final mission, it tells Ann that he has read of his father’s arrest. He is convinced of Joe’s guilt and tells Ann that he is going to kill himself during the mission. Joe suddenly realizes that to Larry all the pilots who died were Joe’s sons. Joe goes into the house, and moments later a shot is heard. The play closes with Chris cradled in Kate’s arms: her final words are “Forget now. Live.”