The fifteenth volume in the Oz series and the first to be written following L.Frank Baum's passing is The Royal Book of Oz (1921).When Professor Woggle-bug informs the Scarecrow that he has no family, he becomes distraught and returns to the cornfield where Dorothy Gale discovered him to look for his "roots." He doesn't come back, so Dorothy and the Cowardly Lion go in search of him.They encounter Sir Hokus of Pokes, an aged knight. They also encounter the Comfortable Camel and the Doubtful Dromedary.They go on a number of strange experiences while looking for the Scarecrow.In this book, the Scarecrow learns that he formerly lived as a person.He was the ruler of the Silver Islands, a nation made up of people that resemble Chinese people and situated far below the Munchkin area of Oz.The spirit of the changed Emperor entered the scarecrow's body when the farmer set him on the beanpole, bringing him to life.The Yellow Knight of Oz has Sir Hokus, the Comfy Camel, and the Doubtful Dromedary as its main protagonists.Once at the Silver Islands, Dorothy and her group rescue the Scarecrow from the locals and take him back to the Emerald City.The Scarecrow makes the decision to go back to Oz and carry on with his carefree life there.