At the end of the play, Chris finally gets through to his father when he reads him Larry's letter to Ann. In the letter, Larry states,
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 any more.
At this point, Joe accepts that his actions in selling the cracked cylinder heads to the army led to the death of twenty-one pilots and to the suicide of his beloved son. He fully realizes for the first time that he was responsible for the death not only of his son but of other flesh-and-blood human beings just like his son. The dead pilots are no longer simply names on a casualty list, but real people to him.
Joe goes in the house. Both Mrs. Keller and Chris believe he is putting his jacket on so he can go and turn himself in for his crime. Mrs. Keller attacks Chris by saying that the war is over and that there is no value now in Joe sitting in prison. She says desperately that they are sorry over what happened, but what else is to be done at this late date? Chris responds by saying,
Once and for all you can know there's a universe of people outside and you're responsible to it.
At this point, they hear a gunshot from inside the house. Joe has committed suicide over guilt at what he has done. Mrs. Keller begins crying out her husband's name, while Chris turns to her and says he never meant for his father to kill himself.
The play ends tragically with Joe's death, but at the same time. it reminds us that we live in a bigger world than ourselves and our immediate families.