Keeper of the Lost Cities is an upper-middle-grade fantasy series by Shannon Messenger that has appeared on the New York Times Best Seller list[1] for a total of ten weeks.

The protagonist of the series, Sophie, is a twelve-year-old elf with telepathy who lives in San Diego, California with a human family.

He discusses the reality of their world with Sophie and tells her that she has to move to the Lost Cities—a place unknown to humankind where elves, trolls, ogres, goblins, gnomes and dwarves live in harmony.

Later in the series, Sophie is desperate to find out who her biological parents are, believing it to be the best solution, otherwise she would be unmatchable, meaning she would be looked down upon if she married someone not on her match list.

"[citation needed] On January 11, 2021, it was announced that Ben Affleck would be directing an adaptation of Keeper of the Lost Cities for Walt Disney Pictures.