Ordinary Mary—an ordinary girl from an ordinary school, on her way to her ordinary house—who stumbles upon ordinary blueberries. When she decides to pick them for her neighbor, Mrs. Bishop, she starts a chain reaction that multiplies around the world. Mrs. Bishop makes blueberry muffins and gives them to her paperboy and four others—one of whom is Mr. Stevens, who then helps five different people with their luggage—one of whom is Maria, who then helps five people—including a man named Joseph who didn't have enough money for his groceries—and so on, until the deed comes back to Mary.