Shirley Jackson's "The Possibility of Evil" was published on December 18, 1965, in the Saturday Evening Post, a few months after her death. It won the Edgar Allan Poe Award in 1966 for best mystery short story. Jackson's tale is a wonderful study into the nature of appearance versus reality. It also relies heavily on literary devices such as foreshadowing and irony.

Miss Strangeworth is the story's main character. In her seventies, she has spent her entire life in the town where she was born, believing her family is more responsible than any other for fostering the community to its current level of success. She takes pride in the part her grandfather played in the town's growth when he started a lumber mill. She also feels her family has not gotten enough credit: no statue, for example, has been erected in her family's honor. With this is mind, Miss Strangeworth has a strong sense of proprietary pride as she walks along and visits with her neighbors.

Miss Strangeworth takes particular care of her appearance. She never goes out in public without having attended to every detail of her hair and clothing. It is important that she appears proper in every way. She is extremely conscious of status. Even though she attended school with Tom Lewis, the town's storekeeper, after graduation Miss Strangeworth has referred to him only by his surname. Calling him "Tommy" is no longer appropriate, nor is their high school friendship.

As the story begins, Miss Strangeworth visits Lewis's grocery store to purchase a few items. She expects Mr. Lewis to know what she wants because it is Tuesday, and she always buys the same thing on Tuesdays. While there, she notices signs of worry on the faces of those she meets. She assesses the cause of each person's stress, making the reader aware that she knows a great deal about the personal lives of those in her community.

As Miss Strangeworth heads home, she meets Mrs. Crane, a new mother with her baby. Mrs. Crane is nervous about her infant, sharing worries with Miss Strangeworth that perhaps the baby is not developing quickly enough. Miss Strangeworth assures the mother that all is well, hinting that perhaps Mrs. Crane is expecting too much too soon from the little one.

They part ways and Miss Strangeworth returns home, passing her garden of lovely roses. Their fragrance fills the air, and she is very proud of them. The old woman goes inside and carries out her routine of putting away her purchases, pridefully noticing the lovely items in her home (including roses from her garden, placed in vases in several rooms).

Moving through the house, Miss Strangeworth goes to her desk and unlocks it. Ignoring the beautiful stationery with her name at the top, she selects colored paper from a cheap supply purchased at the newspaper shop. The colored sheets are used throughout the town for a variety of purposes, and the envelopes are often used to hold household odds and ends or even cookies for a lunchbox.

Miss Strangeworth ignores the beautiful gold pen on the desk and picks up a stubby, dull pencil. In childish print, on a pink sheet, she writes a note about people who should not have children, especially when the child they have is an idiot. Adela Strangeworth writes carefully so as to avoid mistakes. If and when this ever does occur, she takes the sheet to the kitchen and immediately burns it at the stove.

When she is finished, pleased with the results of her first note, she chooses a green page. This one is for Mrs. Harper and suggests that all her friends are laughing behind her back because her husband is having an affair and "the wife is always the last to know." She addresses a green envelope, and then a pink one for her first letter to the Cranes.

As the self-appointed guardian of her town, Miss Strangeworth feels it imperative to tell these "truths" to the members of her community. Of course, she "never concerned herself with facts." If it is possible that something is taking place that someone should be aware of, it is her duty to bring it to his or her attention.

She has already sent a note to Mr. Lewis that his grandson has been stealing from the petty cash. She has alerted Miss Chandler, the librarian, that her gentleman-friend's first wife died under suspicious circumstances. And she has reported to Linda Stewart's parents that their daughter has been behaving inappropriately with the Harris boy, although she doubts anything was really going on at all. However, with so much evil in world, Miss Strangeworth believes she must fight it, especially as there is only one of her kind left. And besides answering the call to duty, she likes writing the letters.

Just before closing her desk, she decides to write one more note. She picks up a blue sheet and addresses it to Mrs. Harper, who is about to undergo surgery. Miss Strangeworth cautions the other woman that doctors make mistakes, and if he accidentally slips with the scalpel, he will still get paid, probably with an incentive from her nephew. She chooses a matching envelope, and still using her block letters, she writes the address on the front.

Miss Strangeworth has been writing her letters for over a year now. She never receives responses because she sends them anonymously. She pauses and thinks that she might write another, but she knows there is plenty of time. There is always evil about. To keep up with it, she will simply have to continue to be watchful and report her suspicions. Feeling a sense of accomplishment, she locks her desk and puts the three letters in her purse. She will mail them when she takes her evening walk.

In the kitchen, Miss Strangeworth makes her midday meal. She sits at her dining room table, which seats twenty-two people. She eats on expensive china with silver utensils. She enjoys this routine: the elegance and comfort of living graciously. She would not have it any other way. Cleaning up, Miss Strangeworth goes upstairs for her nap, surrounded by the scent of her lovely roses. When she wakes, she prepares for her evening walk. She makes her way to the post office, speaking and nodding to those she meets along the way. She makes sure to time her arrival so that it is almost dark, when the post office is closed, but a group of young people are gathered around the building.

Passing Linda Stewart and Dave Harris, she can hear the girl crying, telling the boy that they cannot see each other anymore. He cannot understand what he has done, and Linda can do little more than explain that her parents will not allow it; the reasons are nasty, she says tearfully, reasons only someone with a dirty mind would even consider.

As Miss Strangeworth moves to the mail slot, she inadvertantly drops one of the letters on the ground. She moves away without noticing. Dave Harris tries to draw her attention to it, but she does not hear him because she is considering the need to send the Harris boy's father a letter to put an end to the boy's "potential badness." Dave Harris kindly decides he will walk the letter to the recipients, the Cranes, believing that perhaps it contains good news for them.

Oblivious, Miss Strangeworth continues home and goes to bed. The next morning, she awakes with a sense of pleasure, knowing three letters will be opened today. As she does every morning, she washes up and dresses carefully for the day.

As she comes downstairs and picks up the mail, she immediately notices a letter addressed to her on the same green-colored paper used for her special letters. On the front is the same block lettering she uses. She knows it cannot be a returned letter because she never uses a return address. She shows no concern as she opens the letter, but when she reads it, she silently begins to cry, ironically, over the wickedness in the world. The note reads: "LOOK OUT AT WHAT USED TO BE YOUR ROSES."