"The Monster of Walnut Grove" is a Halloween-themed episode of the TV series Little House on the Prairie. It was first broadcast in the United States on November 1, 1976.
It is Halloween Eve, while Laura is telling Carrie scary bedtime stories. Mary and Laura leave to go to a Halloween party. When Laura and Mary decide to deface the Olsen house, Laura hears Nels and Harriet Olsen arguing and she sees him cut her head off with a sword. Nels comes out and tells Laura that it is their secret and Laura runs home.
Laura tells everybody in town the next day but nobody belives her. Then she tells Carl Edwards and he belives her, not knowing that she had left to go visit her sister. Carl and Laura tell Willie and Nellie but they do not belive them. However, when they get home to eat they see a stain on Mrs. Olsen's apron that looks like blood. At first they are scared but they soon find out that it is not a bloodstain and they decide to play a joke on Laura.
Willie says that he belives Laura and Carl's story and he says that he had heard Nels digging in the cellar in the store. He tells them to meet him in the store at midnight that night. Nellie and Willie come up with a plan. Nellie puts a ghost costume on and hides behind the cellar door. Willie leads them down into the cellar, Nellie scares them, they run off and lock Nellie and Willie in the cellar. While they are running they see Mrs. Olsen in the window. They find out it was just a statue that Nels had cut the head off. They find the head and roll it into the cellar. They hear Nellie and Willie scream and they run away laughing, but then in their minds they see the Headless Horseman coming straight towards them.