The End of Oz by Danielle Paige
This is the fourth and final volume of the Dorothy Must Die series. It picks up where the third volume, Yellow Brick War, ends with Dorothy back in Oz, now with her high school friend Madison. They and her Oz boyfriend Nox are in Ev to defeat the Nome King.
As with the previous three novels in the series Danielle Paige shows a good grasp of the Baumian characters of Oz, and has a clever way of modernizing them to make them of interest to a modern Young Adult audience. Each book introduces more of Baum's characters, and in this volume they meet the Wheelers, and Princess Langwidere.
In this final book both Amy and Dorothy narrate alternating chapters so we finally get to see Dorothy as something other than the evil enemy. She has been taken captive by the Nome King who plans to marry her to steal her magic.
Like the first three, Yellow Brick War is best read as part of the series, as the story picks up and ends abruptly. Could the author be planning to continue the series? I gave the book four stars instead of five because I feel the author is, at times, too free in her adaptation of Baum's characters, revisioning them for a modern audience in a way that is jarring and discordant to people who know them well from reading Baum's books.