The book starts in 1906. Dorothy, now a teenager, is on vacation in San Francisco when the earthquake of April 18 leaves her trapped in a hotel elevator. Back in Oz, there is a war going on over the Restwater Lake. Glinda is held under house arrest due to allegations of treason. Most of Glinda's staff have been executed, but a few remain, including a strange servant child named "Rain".
Out of Oz provides examples of:
- All of the Other Reindeer: Dorothy's peers shun her because of her fantasies about Oz. They don't say anything to her face because of their Christian beliefs, but they do ignore her.
- Bookends: The final sentence "A mile above anything known, the Girl balanced on the wind's forward edge, as if she were a green fleck of the sea itself, flung up by the turbulent air and sent wheeling away." mirrors the starting sentence of the first book "A mile above Oz, the Witch balanced on the wind's forward edge, as if she were a green fleck on the land itself, flung up and sent wheeling away by turbulent air."
- Chastity Couple: Brrr and Ilianora. For obvious reasons.
- Cloud Cuckoolander: Rain. Up to 11.
- Friend to All Living Things: Rain has shades of this.
- An Ice Person: Glinda and Rain use the Grimmerie to freeze a group of dragons that are being used to attack Munchkinland.
- Interspecies Romance: Fiyero's daughter Ilianora informally marries Brrr. Their marriage is a Chaste romance due to their bodies being incompatible.
- Magic Carpet: The Bear working Broken Things Of No Use To Anyone But You tells Rain and Tip that they're standing on a flying carpet and explains that it's full of flies.
- Mythology Gag:
The green rice otter was swaying back and forth, defying gravity, having a modest little carnival ride for itself.
- Rain quotes words sung by her grandmother Elphaba in the musical during the number "I'm Not That Girl".Rain: "Don't wish, don't start. Wishing only... note
- Other examples, though they may be a stretch, might include Dorothy singing about rainbows, a section entitled "Somewhere" (as in 'Somewhere over the Rainbow' from The Wizard of Oz), and Brr being called King of the Forest.
- Even more of a stretch might be Dorothy repeating in sing-song 'Maybe this time...', which could be looked at as a shout out to Kristin Chenoweth who sang that song on Glee and who played Glinda in the musical. To say nothing of Liza Minelli, Judy Garland's daughter, who sang that song a long time before Cheno introduced it to the tweens of the world.
- It's been six years since Dorothy went to Oz. She's now a sixteen year old girl. Dorothy's actress Judy Garland was sixteen when she played her in the MGM film.
- One line references the musical number "Defying Gravity" from the musical:
- Rain quotes words sung by her grandmother Elphaba in the musical during the number "I'm Not That Girl".
- Nephewism: Rain is eventually taken care of by her aunt Ilianora.
- Shout-Out: To Charlotte's Web, where Rain asks if the spiders could write words in their webs for her to read. Mr. Boss says that would be "some spider". The first words Charlotte wrote in her web were "some pig".
- Sweet Polly Oliver: Tip is eventually revealed to be Ozma Tippetarius. This is in canon with The Marvelous Land of Oz. Though there it was an actual Gender Bender.
- Time Skip: Out Of Oz skips again to Rain (born at the end of the second book) as a child of seven or so, and proceeds to follow her more or less continuously until the age of sixteen.
- The Unreveal: Throughout the series there are clues that Elphaba might not be dead or that she might somehow have been resurrected. Out of Oz ends with rumors that Elphaba might have come back from Mombi's spell but it's never revealed if she did. The final chapter has an ambiguous scene where Glinda's jail cell is opened by a person. Glinda clearly knows them and says "You wicked thing.".