At the beginning of All My Sons, Annie Deever has just come to visit the Kellers. Joe and Kate Keller are the parents of Chris Keller, as well as his brother Larry, who died in the war. In the middle of the night after Annie’s arrival, a tree dedicated to Larry has just been struck by lightning and broken down. This brings about a conversation between Chris and Joe, in which Chris tells Joe that the two have made a mistake in letting Kate continue to think that Larry is alive. Later on, Chris reveals to Joe a fact Joe had already guessed: he invited Annie—who once was involved with his dead brother, Larry—to visit because he wants to ask Annie to marry him. However, Kate’s refusal to accept that Larry is dead presents a significant barrier to Chris and Annie’s marriage, because as long as Kate believes that Larry is alive, she will see Annie as Larry’s girl.

Kate and Joe discuss Annie and Chris, and Kate reveals her awareness of the reason for Annie’s visit. But she condemns the two’s desire to get married, saying that it is wrong because Larry is still alive and begging her husband to believe with her in Larry’s survival. When Annie returns, Kate tells Annie that Annie waiting for Larry affirms Kate’s own faith that Larry is alive. It unfolds that Annie’s father is in prison because of an incident that happened during the war. He worked with Joe at Joe’s factory and discovered that there were a number of defective parts that were about to be shipped out to be put in planes for the war. The court held that Annie’s father was responsible for shipping them out, while Joe was not, and Joe maintains that this is true. He also tells Annie that when her father gets out of prison, he is willing to forgive him for testifying against him and even take him back into business. The parents go inside, and Chris asks Annie to marry him. She accepts. Then she is called inside because her brother George is on the phone, calling from the place where her father is imprisoned. He wants to visit the Kellers.

George arrives and tells first Annie and then Chris that he now believes that Joe was responsible for their father shipping out the defective airplane parts. Joe had claimed that he had the flu and had asked Annie’s father to take care of things at the factory. However, George tells the two that his father told him that Joe had actually been in touch with him that day. Their father called Joe to ask him what to do about the defective parts, and Joe told him to just ship them. Annie and Chris refuse to believe this. After talking with the older Kellers for a bit, George goes away. Chris and Joe confront Kate with the reality of Larry’s death, but Kate says that she cannot accept it because if she does, she has to accept that Joe is guilty of it. This is the source of Chris’s realization that his father really is guilty. Heartbroken, he leaves.

However, Chris does eventually return to confront his father. Joe ultimately admits exactly what happened and claims responsibility, though he does say he did it for his family and gets angry about it. After a lengthy confrontation with Chris, Chris tells his father that he is moving away. He can’t stand to live at home knowing what he knows, but he can’t turn his father in either. In desperation, Joe agrees to turn himself in rather than break Chris’s life permanently. Chris grimly consents to drive his father to turn himself in. Inside the house, once Joe has gone in, a shot is heard. Chris goes in to see what has happened and calls for the doctor to be sent. Then he and his mother embrace and cry, beginning to grieve over yet another family member they have lost. There is a sense that the cycle of loss, grief, and denial will begin again, taking away from the Keller family and Annie what peace and acceptance they may have achieved over the course of the last three years and the way things have developed during the play.