Mark and his sister Jodie visit their grandparents for a month every summer. The two have fond memories of previous summers on the farm.
Mark and Jodie notice things are different on the farm: their Grandma Miriam no longer makes them chocolate chip pancakes, their Grandpa Kurt no longer tells them scary stories, and new scarecrows have popped up all over the farm and appear to move.
Mark assists Jodie in scaring Sticks, who Jodie thinks is responsible for the scarecrows moving, by dressing up as a scarecrow and waiting in the cornfield. When Jodie's plan goes sour and Sticks' father, Stanley wakes up the scarecrows, Mark learns that dressed as a scarecrow, the scarecrows obey him. He pulls his mask off, causing the scarecrows to imitate him and pull their heads off.
The headless scarecrows descend on Mark and his family until Sticks arrives with torches and burns them down to ashes.
Mark's defining character trait is laziness. Jodie, who narrates the story, complains about how slow Mark moves. Mark tries to pawn his backpack off on Jodie at the beginning of the book because he doesn't want to carry it himself. He brought a Game Boy, comic books, and an iPod to the farm, intending to spend the summer lounging around. He complains about having to do anything physical in the book.
Mark is extremely agreeable. He doesn't argue with his sister, and goes along with the flow.