Keeper of the Lost Cities – Book 10 Update
Release Date and Title (Tentative): Simon & Schuster’s official listing for Keeper of the Lost Cities #10 gives a publication date of November 5, 2026 (UK/Children’s). No official subtitle or name has been announced – the book is currently referred to simply as Keeper of the Lost Cities 10. In fact, the publisher’s announcement (AP News) in 2021 described the 10th book as “currently untitled”. (Earlier press had slated Book 10 for 2023 as the final volume , but that schedule has since slipped.)
Plot Details: At this point there is no official synopsis for Book 10, but interviews hint at the core story threads. Messenger has said Book 10 will involve the fallout of Keefe’s journey through Humanland. In a late-2024 Publishers Weekly interview, she confirmed that “there are some really big secrets that Keefe is keeping” which will come out in Book 10. (She noted that the events of the new Book 9.5 ( Unraveled , from Keefe’s POV) must be woven into Book 10’s narrative to make those revelations feel organic .) In short, Book 10 is expected to focus on Sophie learning what Keefe discovered, and the emotional implications for their relationship. Messenger has promised the book will reveal “all of the secrets that readers have been dying to know since book one” and deliver an “epic” conclusion.
Series Conclusion: Book 10 was originally announced as the series finale. In the 2021 Aladdin/S&S announcement, Messenger said the 10th volume would conclude Sophie’s story and reveal all remaining mysteries. (She explicitly called it the “final conclusion” of the saga .) In recent remarks she has likewise stressed winding down the series and answering big questions. However, she has hinted that if necessary she may extend the series beyond ten books to cover everything (no formal 11th book is confirmed). In short, Book 10 is intended as the big finale, though Messenger is keeping options open in case any major plotlines require further volumes.
Delays and Updates: Book 10’s release has been delayed from earlier plans. The author announced in March 2023 that she was expecting her second child, which pushed the timeline for writing the book (no new date was given). In early 2024 Shannon Messenger also released a special novella ( Unlocked , Book 8.5) and then Book 9.5 ( Unraveled ) in November 2024, further delaying the main series’ conclusion. As of mid-2025 no firm new release date for Book 10 has been announced. However, the paperback edition of Unraveled (out Nov 11, 2025) is confirmed to include a “bonus sneak peek” (first chapter preview) of Book
. This suggests Book 10 will follow sometime after late 2025 – consistent with the late-2026 listing on S&S’s site. In summary, Messenger and her publisher have confirmed that Book 10 will be released (eventually) but have not yet named it or given a final date. Watch for the planned sneak-peek in Unraveled (Nov. 2025) and publisher announcements later in 2025 or 2026 for full details.
Sources: Official publisher and news reports and author interviews were consulted. Release plans come from Simon & Schuster’s site and AP News/Spectrum (2021). Author comments (Interviews/ Q&As) describe story clues. Retail listings (Barnes & Noble) confirm the Unraveled paperback (Nov. 2025) will include a preview of Book 10. All cited information is up-to-date as of Fall 2025.
Sources
Keeper of the Lost Cities 10 | Book by Shannon Messenger | Official Publisher Page | Simon & Schuster AU https://www.simonandschuster.com.au/books/Keeper-of-the-Lost-Cities-10/Shannon-Messenger/Keeper-of-the-Lost-Cities/ 9781398523838
One last ‘Keeper of the Lost Cities’ scheduled for 2023 https://spectrumlocalnews.com/nc/triad/ap-top-news/2021/10/13/one-last-keeper-of-the-lost-cities-scheduled-for-
Q & A with Shannon Messenger https://www.publishersweekly.com/pw/by-topic/childrens/childrens-authors/article/96600-q-a-with-shannon-messenger.html
Unraveled Book 9.5 by Shannon Messenger, Paperback | Barnes & Noble® https://www.barnesandnoble.com/w/unraveled-book-95-shannon-messenger/
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