After the mild disappointments of Son of a Witch and A Lion Among Men, this fourth volume brings the "Wicked Years" series to a satisfying conclusion.
The principal surviving characters from the first three volumes return -- Glinda; Elphaba's son, Liir, and his wife, Candle; the Lion Brrr (who doesn't much appreciate the whole "Cowardly" thing) -- and they spend much of the book wandering around Oz, trying to protect the Grimmerie, the immensely powerful book of magic that may be the key to ending the civil war between Munchkinland and the rest of Oz.
The major new character is Liir and Candle's daughter, Rain, who as the female descendant of Elphaba -- hereditary government in Oz is matriarchal -- is also being hunted by both sides. And there are return appearances by a few characters who've been absent from the scene for some time.
The book takes place over the course of ten years or so, and Maguire's not always as clear as he could be about indicating how much time has passed since we last saw character X. He's also a bit too fond of winking references to Judy Garland and the 1939 movie, as though Dorothy and Judy Garland were one and the same; a reference to the Emerald City being overrun by Dorothy impersonators was a bit much, for instance.
But the plot lines left dangling from earlier volumes are mostly wrapped up here, and Maguire's characters are rich and convincing; I was always fond of his Glinda, and it's nice to see her get a good-sized role here.
This is billed prominently as "the final volume in The Wicked Years," which it well may be. But there is ample room for Maguire to return to Oz (perhaps under a new series name?); several of his characters are left at the beginnings of new phases in their lives which would make interesting stories, and there's an entire pre-Wicked history of Oz that could be fruitfully explored. And given the relative lack of success of his non-Oz novels, I'd be quite surprised if he doesn't eventually find some reason to get back there.