In "Scalawagons", Neill exploits two characters he introduced in his previous book, "The Wonder City of Oz", Number Nine and Jenny Jump. Jenny is the book's protagonist, though the story begins with Number Nine, who is now an assistant to the Wizard of Oz. The Wizard has a tendency to disappear suddenly, as he pursues various projects. His latest project is the creation of a new form of transportation for the Land of Oz. In a red-domed facility atop Carrot Mountain in the Quadling Country, the Wizard has established a factory to build scalawagons, intelligent cars that can also fly. (They spread their running boards like wings.) In his illustrations, Neill makes them resemble the "kiddie cars" of amusement-park rides; their heads are in turrets on their roofs.