On May 22nd, 2018, Shannon Messenger announced that there will be a ninth book in the Keeper of the Lost Cities series. It is scheduled to be released in the fall of 2020. The previous book is Legacy, which was released on November 5, 2019. It will most likely include a Short Story as the past three books (Book 6: Nightfall, Book 7: Flashback and Book 8: Legacy) have.
What we know
- The cliffhanger from Legacy will be resolved. Source - Shannon Messenger book talk.
- New art will be released with the coming of this book.
- The questions we have will be resolved.
- Keefe will be in a coma because of the ending in Legacy.
- This may be the last book of the series. If Shannon Messenger doesn't have room/time to finish the story, there will be a tenth book.