Miss Strangeworth is spreading suspicion all over town with her anonymous poison-pen letters, but she thinks she is only being helpful and does not realize how much harm she is doing. When she goes to the grocery store she notices that Mr. Lewis the proprietor is not his usual self. He is polite but somewhat distant and distracted.
Mr. Lewis looked worried, she thought, and for a minute she hesitated, but then she decided that he surely could not be worried over the strawberries. He looked very tired indeed...
At this early point in the story the reader could not suspect that Miss Strangeworth might have anything to do with the grocers worried and tired air. He is only a minor character in the story and is used to exemplify what seems to be happening all over town. Miss Strangeworth has noticed this.
Many people seemed disturbed recently, Miss Strangeworth thought.
When Miss Strangeworth gets homes and starts writing more of her poison-pen letters, we realize why Mr. Lewis seemed worried and tired.
Mr. Lewis would never have imagined for a minute that his grandson might be lifting petty cash from the store register if he had not had one of Miss Strangeworth's letters.
Her letters do not make positive accusations. They only offer suggestions about possibilities of evil. If her output of three letters that day was average, then she could have been sending out almost a thousand of her letters during a year. She is a real troublemaker, but she is not conscious of her motives. She may believe she is just being helpful, but all her letters suggest that she is an unhappy woman who does not like to see others enjoying happy relationships. Mr. Lewis's relationship with his nephew will be poisoned. She has poisoned the relationship between the two high school kids, Linda Stewart and Dave Harris, who are in love. She is poisoning the happiness of the Cranes by suggesting that their six-month-old baby may be mentally defective and that they should not be thinking of having a second child. She poisons the relationship of a middle-aged couple named Harper by suggesting to Mrs. Harper, a close acquaintance, that her husband might be having an affair with another woman and that everybody in town might know about it. And she suggests to old Mrs. Foster that her nephew might be thinking of having her killed.
In all the letters we can see the motivation of envy and jealousy, although Miss Strangeworth cannot recognize it herself. She is not unlike a lot of sweet old ladies we encounter in life who spread gossip and create trouble because they are lonely and unhappy. She is only an extreme example. She can make bad things happen just by planting suggestions that they might.