For a three-act plot analysis, put on your screenwriter’s hat. Moviemakers know the formula well: at the end of Act One, the main character is drawn in completely to a conflict. During Act Two, she is farthest away from her goals. At the end of Act Three, the story is resolved.
Act I
Joe Keller is on orange alert. His defenses are raised by the accident of Larry's tree blowing down, by his wife Kate's anxiety, and mostly by the arrival of Ann, the daughter of the man he landed in prison. Chris's intention to marry this girl causes conflict in the family.
Act II
Ann's brother George arrives, upping the danger. He accuses Joe outright and tries to take Ann away, but she refuses. At the end of the act, everyone knows it's true. Joe killed people and ducked the consequences.
Act III
Chris confronts his father. A letter proves once and for all not only that Larry's dead, but that he killed himself because of Joe's actions. All the questions are answered; the past is aired. Joe shoots himself.