Three and a half years before the events of the play, Larry Keller was reported missing in action, while flying a mission off the coast of China.
His father, Joe Keller, was head of a business which made aero engine parts. When, one night, the production line began to turn out cracked cylinder heads, the night foreman alerted Joe's deputy manager, Steve Deever as he arrived at work. Steve telephoned Joe at home, to ask what to do. Worried by the lost production and not seeing the consequences of his decision, Joe told Steve to weld over the cracks. He said that he would take responsibility for this, but could not come in to work, as he had influenza. Several weeks later twenty-one aeroplanes crashed on the same day, killing the pilots.
Investigation revealed the fault in the cylinder heads, and Steve and Joe were arrested and convicted. On appeal, Joe denied Steve's (true) version of events, convinced the court he knew nothing of what had happened, and was released from prison. Before his last flight, Larry wrote to his fiancée, Ann, Steve's daughter. He had read of his father's and Steve's arrest. Now he was planning suicide.
Three and a half years later, Ann has told no-one of this letter. Kate Keller knows her husband to be guilty of the deaths of the pilots and has convinced herself that Larry is alive. She will not believe him dead, as this involves the further belief that Joe has caused his own son's death, an intolerable thought. She expects Larry to return, and keeps his room exactly as it was when he left home. She supports Joe's deception. In return she demands his support for her hope that Larry will come back. Ann and her brother, George, have disowned their father, believing him guilty. But George has gone at last to visit his father in jail, and Steve has persuaded him of the true course of events.
The play opens on the following (Sunday) morning; by sheer coincidence, Ann has come to visit the Kellers. For two years, Larry's brother, Chris, has written to her. Now he intends to propose to her, hence the invitation. She is in love with him and has guessed his intention. On the Saturday night there is a storm; a tree, planted as a memorial to Larry, is snapped by the wind. Kate wakes from a dream of Larry and, in the small hours, enters the garden to find the tree broken.