What are some contrasts/comparisons between the short stories "The Possibility of Evil" and "Lamb to the Slaughter"?
In both of these stories, the main character is an outwardly placid and peaceful woman who possesses a malicious intent. Whether or not you call Mary Maloney's act one of passionate revenge or not, we can agree that murder is malicious and she was capable of it. As for Ms. Strangeworth, her malicious intent involves criticizing all her neighbors and publicly exposing their sins.
What both authors are thematically doing with these seemingly innocent women is to show the dark underbelly that exists in small town America. Both Mary and Ms. Strangeworth are upstanding citizens in their towns, and the towns themselves are portrayed as being quaint - small enough that Mary knows the grocery and all the police officers; small enough that Ms. Stangeworth can know the most intimate details of her neighbor's lives.
It isn't just the acts of these women, though (or at least, the initial acts). For "Lamb", it is the way Mary follows through. Despite having murdered her husband, she is able to cook up the murder weapon to serve to the cops with a straight face. She even giggles at the irony of it. For "Possibility", it is the way the town followed through. Strangeworth isn't the only evil resident - the retaliation that occurs (destruction of the roses) when townspeople discover her identity prove that some form of immorality exists in us all.