In a prologue, Douglas Fairbanks appears in a chef's outfit mixing a cake with action, mystery, adventure, romance and comedy, seasoned with pep and ginger. The finished cake is The Knickerbocker Buckaroo. The story begins as buoyant Teddy Drake, expelled from his exclusive Fifth Avenue club for playing practical jokes and leaping over furniture, decides to reform his selfish impulses. Anxious to do "something for somebody," he boards a train bound for the Southwest. After helping an old woman off the train, Teddy takes the wrong train and meets Manuel Lopez, a Mexican bandit, going to visit his sick mother. To hide Lopez from a crooked sheriff, and because Teddy left his shirt in the first train, Teddy exchanges clothes with him. At the border town of Sonora, the sheriff chases Teddy along the roofs until, seeing a girl in jail, Teddy lets himself be arrested. Learning that the girl, Rita Allison, has money hidden that the sheriff wants to steal, Teddy escapes. After Lopez saves him from a lynching, Teddy finds the money, holds off the sheriff's gang until a U.S. Marshal arrives, and then returns to New York with Rita, now his fiancée.