O’Connor uses the setting of the story to lure the reader into a state of comfort before unleashing the darkness the Misfit represents and the darkness of the Grandmother’s soul. The grandmother thinks she is a good woman and by all external appearances, she is. However, just like the pretty rural countryside they drive through, there is something hidden beneath the surface.
By setting the story in the rural, quiet countryside, O’Connor gives the reader a sense of calm and comfort before introducing the violence of the story which is supposed to jar the reader into reflection. Initially, the story meanders along with the family taking a road trip. . Even the stop at Red Sammy’s where the family find out about the Misfit escaping from jail are described visually as pleasant. Additionally, most place names and areas are vague to give the reader the idea that this violence can happen anywhere, especially where you least expect it.
The grandmother becoming mistaken about where the old plantation house is, can be seen as a metaphor for the path her life has taken. She thinks she is a good woman and that she is righteous in her beliefs but just like the pastoral landscape the family travels through, there is hidden darkness or evil lurking where you least expect it.
The setting relates to the theme very directly. That is to say, the bulk of the story happens inside, within a domestic setting. We are told the following: "There stood, facing the open window, a comfortable, roomy armchair. Into this she sank, pressed down by a physical exhaustion that haunted her body and seemed to reach into her soul."
Mrs. Mallard is contained by the walls of the house as her life has been by society and her husband. Right now, though, the news of his death creates "the open window," a symbol of the possibility of change. The landscape visible through the window symbolizes the realms of new hope she might enter. However, before she can go out into that world, her husband re-enters the house/her life, killing her.