The main idea of Roald Dahl’s scary short story “Lamb to the Slaughter” is that you shouldn’t underestimate people who seem weak, and that people who seem innocent aren’t always what they seem to be. Even though Patrick might have deserved what he got, this story is about how people miss Mary’s potential until it’s too late.
In the story “Lamb to the Slaughter,” there are many ways in which people underestimate what will happen. The first instance happens when Patrick comes home and tells Mary that he is leaving her. He knows that she is pregnant, but he just tells her that it is important to be calm and reasonable about a divorce, saying that he will send some money to help her take care of the child. When she tells him he can’t go, he finally snaps at her, “Try to stop me!” Mary kills him with a leg of frozen lamb.
Patrick is a police detective, and when his coworkers come to investigate the crime, they don’t even think of Mary as a suspect, even though statistics show that spouses are often one of the most common killers.
As the hungry police officers eat the leg of lamb that was still in the oven, they don’t even think about it being the weapon, even though it would have been the perfect size and shape (when frozen).