Overall, there are 14 books in the Oz franchise, and The Emerald City of Oz is the 6th consecutive novel. In '87, the Canadians adapted it into a pretty awesome animated movie. As for the book, it was published 100+ years ago, in 1910, and they say that Baum didn't want to write any more stories in the series, but, due to some financial difficulties, he ended up writing 8 more.
Dorothy is a girl with a vivid imagination and is always telling all kinds of peculiar stories to her uncle and aunt. It goes without saying that these stories are nothing more than just a figment of her dreamy nature. Well, at least that's what her relatives think. However, she did actually go through every little adventure from her "tales" and loves to share them with her friends and family.
In the previous book, the cyclone devastated the farmhouse of Uncle Henry and Aunt Em, leaving the man of the house with a huge debt. Taking out a mortgage on his lovely farm was the only way for him to pay, and now, if he fails to repay the folks that he took the money from, they will gain complete control over the farm. Obviously, Henry can't let his family be stranded out there on the streets.
Land of Oz works:
1. The Wonderful Wizard of Oz (1900)
2. The Marvelous Land of Oz (1904)
3. Ozma of Oz (1907)
4. Dorothy and the Wizard in Oz (1908)
5. The Road to Oz (1909)
6. The Emerald City of Oz (1910)
7. The Patchwork Girl of Oz (1913)
8. Tik-Tok of Oz (1914)
9. The Scarecrow of Oz (1915)
10. Rinkitink in Oz (1916)
11. The Lost Princess of Oz (1917)
12. The Tin Woodman of Oz (1918)
13. The Magic of Oz (1919, posthumously published)
14. Glinda of Oz (1920, posthumously published)
Em is ready to face it all with her husband, but they're both concerned about Dorothy's future. The girl overhears them talk about it, and decides to bring them all to the Land of Oz. She believes that they’ll all be happier and live better lives there. Princess Ozma agrees to help Dorothy and teleports the whole family to her throne room, where they get that "royal treatment". At the same time, the Nome King is about to attack Oz with his horde...