Act Three of All My Sons takes place on the porch of the Keller home. It is now 2 a. m.
Chris has run off and his mother waits for his return, worried. Jim the doctor returns from a house call. He tries to allay her concerns, but he also reveals that he knows the truth about Joe’s crimes.
After Jim leaves, Joe Keller and his wife discuss what should be done. Kate believes that Keller should offer to admit his guilt to the authorities. She does not believe that Chris would allow his father to turn himself in. However, she thinks that by making the offer, it will help Chris adjust to the truth.
This idea exasperates Joe. He does not understand why he needs forgiveness. He argues that his actions are justified because he did it for his family.
Ann steps onto the porch and explains that she has no plans to reveal Keller’s guilt. She just wants to leave with Chris and build a life together.
Kate still insists that Chris must not marry Ann. However, Ann is not deterred. She reveals a letter written by Kate’s son Larry, shortly before he died. It reads:
My dear Ann: It is impossible to put down the things I feel. But I’ve got to tell you something. Yesterday they flew in a load of papers from the States and I read about Dad and your father being convicted. I can’t express myself. I can’t tell you how I feel – I can’t bear to live anymore. Last night I circled the base for twenty minutes before I could bring myself in. How could he have done that? Everyday three or four men never come back and he sits back there doing business… I don’t know how to tell you what I feel… I can’t face anybody… I’m going out on a mission in a few minutes. They’ll probably report me missing. If they do, I want you to know you mustn’t wait for me. I tell you, Ann, if I had him there now I could kill him. [
When Chris returns and discovers the letter for himself, he is furious. He confronts his father and reads the letter aloud to him.
Finally, Joe Keller understands the disastrous implications of his actions. Larry was so distraught about his father’s greed and inhumanity that he purposely crashed his plane, ending his own life to eliminate his agony.
Upon realizing this, Keller reflects upon the twenty-one airmen who died because of him. He quietly says, “I think to him they were all my sons. And I guess they were, I guess they were.” Then Keller enters the house, implying that he will turn himself in.
Moments later, a gunshot is heard. Joe Keller has shot himself, leaving Ann, Chris and Kate stunned and grief-stricken.