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
Act I is seen through the eyes of Mrs. Shortley and begins when we see her watching the arrival of the Guizacs from on top of the hill. As the act continues she grows increasingly suspicious that the Displaced Person will displace her. Her suspicions become reality when she overhears Mrs. McIntyre telling Father Flynn of her plans to fire the Shortleys. Mrs. Shortley reacts by displacing herself, packing up the family and their belongings and leaving the farm for an uncertain future. The shock of this displacement quite literally kills her, though we don't get evidence of this until Act 3 when Mr. Shortley returns to the farm, alone.
Act II
In Act II the point of view switches from that of Mrs. Shortley to that of Mrs. McIntyre. It begins in the middle of Mrs. McIntyre's conversation with Astor about the Shortleys and other employees who have left her over the years. It ends when Mrs. McIntyre confronts Mr. Guizac over the arranged marriage between his sixteen-year-old cousin and Sulk.
Act III
Like Act II, Act III is mostly from Mrs. McIntyre's perspective. It opens in the middle of her conversation with Father Flynn. He's trying to tell her about Jesus. She wants to talk about getting rid of Mr. Guizac. The Act ends with Mr. Guizac's death, and Mrs. McIntyre's loss of her voice and vision. We get a final image of her lying in bed, listening to Father Flynn, her only visitor.