
Last week I started to muse about how
open-ended series are different from those with a planned ending, given how storytellers have to maintain some dramatic tension and character conflicts rather than resolve them. How, one might ask (if one were I), does that apply to
L. Frank Baum's
Oz books?
Baum wrote
The Wonderful Wizard of Oz with no thought to a sequel. Therefore, it ends with the Scarecrow,
Tin Woodman, and Cowardly Lion's problems solved, each established as a ruler of part of Oz. The Wicked Witches are dead,
Dorothy is back home, and we can all go home, too. But the success of that book and especially its stage adaptation prompted Baum to write a sequel,
The Marvelous Land of Oz.
Because
Wizard hadn't left dangling questions or conflicts, Baum had to start
Land with a new set of characters. Oz turned out to have more wicked witches, a missing dynasty, and a rebellious female army. The book features the Scarecrow and the Tin Woodman since they had become stars on stage, and they were still interesting. The Cowardly Lion is nowhere to be seen because a brave lion isn't an interesting character; it's a cliché. Again, Baum finished
Land without expecting to follow it up with any more books about Oz.
The success of both those books, and a generous
contract from Reilly & Britton, convinced him to expand the series further. The next four books constitute the first Oz series conceived as such, with a new title each year. And I think Baum had an overall narrative arc in mind as he wrote them, vague though it probably was.

Baum started by returning to Dorothy and the roots of that character. Even before the cyclone carries her to Oz, what had he written about her? She's a Kansas farmgirl, and the uncle and aunt raising her are old, poor, and sad. Baum's next four Oz books therefore address the problems of Dorothy's family.
The first of that four-book series,
Ozma of Oz, starts with Dorothy and Uncle Henry on a trip to Australia for his health. Along the way, she makes her second journey to fairyland. She meets Ozma (protagonist of
Land), reunites with the Cowardly Lion (once again feeling a lack of courage, and therefore interesting), and becomes a princess of Oz. The second and third books also show Dorothy traveling to Oz, each time with a different animal companion and a different set of humans. Having gone by air in
Wizard, she makes the journey over the water, through the earth, and by magic.
Ozma also introduces the villainous Nome King. Although he's defeated at the end of that book, he's not destroyed like the Wicked Witches. The next titles tie off some loose ends from Baum's previous writing.
Dorothy and the Wizard of Oz brings the Wizard back to the Emerald City and tries to resolve some moral questions about his conduct (in the stage show, the Wizard was a villain).
The Road to Oz unites the Oz books to the universe of most of Baum's other fantasies by having their characters visit Ozma for her birthday.

Finally,
The Emerald City of Oz brings Baum's Oz saga to a close. Dorothy and her family, having lost their farm to a mortgage holder, move permanently to the Emerald City, thus resolving the problems established in the first chapter of
Wizard. The Nome King returns with an army of immortals, but Ozma and her allies manage to dispatch them--seemingly forever--without compromising her values.
Finally, we come to
Glinda, the sorceress who rules the southern part of Oz. In the first two books, she was the
dea ex machina who provided the power and knowledge to resolve the plots. She plays little role in the next three, however. Baum turns to her once again to bring the series to a close. In order to protect Oz from invasion, Glinda cuts off the country from our Great Outside World. The series was over, Baum told his readers. And indeed most of the lingering problems and questions had been resolved.
Bankruptcy due to plowing too much of his money into a new stage show later caused Baum to return to writing Oz books. And when he did, he approached the series as open-ended, without the thematic unity or overall plot of the four books between
Ozma and
Emerald City.