Keeper of the Lost Cities: Guide to Books, Age Rating & Movie

If your kid has developed an obsession with telepaths, secret kingdoms, and Sophie Foster, you’re not alone. The Keeper of the Lost Cities series has built a devoted readership since 2013, with families asking: Is it appropriate for my 11-year-old? Is there really a Disney movie in the works? And when is Book 10 coming out? This guide cuts through the noise to give you the details that actually matter for parents and fans alike.

Author: Shannon Messenger · Protagonist: Sophie Foster · Current Book Count: 11 · Target Age: 9+ · Key Ability: Telepath

Key facts about the series at a glance:

What is the Keeper of the Lost Cities about?

Keeper of the Lost Cities follows twelve-year-old Sophie Foster, a girl who has spent her entire life hiding a dangerous secret: she can hear the thoughts of everyone around her. When Sophie finally confides in her parents, she learns her telepathy is just the beginning. Shannon Messenger’s series drops readers into a world where Sophie discovers she belongs to a hidden elvin world called the Lost Cities, and that she’s been unknowingly entangled in an ancient prophecy meant to save both worlds from destruction.

Plot summary

The series operates on two levels. On the surface, it’s a classic chosen-one fantasy where Sophie must navigate a new school, form friendships, and dodge villains. Dig deeper, and the books explore loyalty, sacrifice, and the weight of secrets kept from the people who love you most. The first book throws Sophie into Foxfire Academy, where students are trained in unique abilities called “talents” — from reading auras to controlling fire.

Main world-building elements

The Lost Cities exist in a parallel world layered above the human “Lost Cities” we know, connected by a mysterious energy. The elvin society is organized by kingdoms, each with distinct political tensions. Sophie isn’t just any elf — her unusual combination of talents marks her as potentially the most powerful member of her species. That positioning draws enemies who see her existence as a threat to the established order.

The pattern across the series so far: each book escalates the stakes while deepening the emotional bonds between characters. By Book 9, readers have watched Sophie transform from a scared, secretive girl into a leader forced to make choices with consequences that ripple across both worlds.

Is Keeper of the Lost Cities appropriate for 11 year olds?

The official answer from publisher Simon & Schuster lands squarely in middle-grade territory: ages 8–12. Book 1 alone sits at 512 pages with a 670L Lexile level, which places it comfortably in upper elementary to lower middle school reading range. Those specs suggest a typical 9 or 10-year-old can handle the text independently, while younger kids might need parental support.

Age rating details

Simon & Schuster’s official recommendation covers ages 8–12 for the entire series. However, a second opinion from Redeemed Reader suggests 12+ with some considerations, particularly as the series progresses. That contrast matters for parents. Early books in the series read like straightforward middle-grade fantasy. Later entries introduce more complex emotional situations and moral gray areas that some families report as appropriate for discussion rather than passive reading.

Content concerns

The series reportedly contains themes that warrant consideration for younger readers despite its middle-grade classification. Redeemed Reader’s analysis points to “strong themes appropriate for older readers,” which suggests content intensity increases as Sophie grows older in the narrative. This fits a pattern common in fantasy series where protagonists age in real-time alongside their readership.

The books don’t shy away from loss, betrayal, and difficult choices. Sophie’s journey includes moments where trusted adults disappoint her, where friends make questionable decisions, and where the right answer isn’t clear. For some 11-year-olds, this depth enhances the reading experience. For others, parents may want to read alongside or discuss specific books.

Common Sense Media review

Parents researching Common Sense Media reviews for the series will find a mixed consensus. The core appeal — fast-paced adventure, memorable characters, and a heroine with unusual abilities — consistently receives praise. Content discussions tend to focus on whether the later books push beyond the “safe” middle-grade space into territory more suited to early teenagers.

Is Disney making a Keeper of the Lost Cities movie?

Disney confirmed a live-action film adaptation on January 11, 2021, with Ben Affleck attached as director and producer through his Pearl Street banner. Kate Gritmon was announced as co-writer, and Madison Ainley came aboard as Executive Producer. That announcement made the project feel like a sure thing — Affleck at the time was coming off strong directorial work, and Disney had been aggressively developing fantasy properties.

Current status

As of 2025, no casting details or release date have been confirmed for the film. The Keeper of the Lost Cities Wiki currently lists Emma Watts as the film’s director, though the source for this change remains unclear and hasn’t been publicly explained. The project appears stalled — which isn’t unusual for adaptations announced with fanfare but then quiet for years. Major studios shelve and restart projects regularly without announcements.

The Dis Insider reported in 2021 that the film adaptation was moving forward with significant talent attached, but no follow-up coverage has confirmed active development. For families excited about a potential movie, the realistic expectation is that nothing is certain until Disney makes an official announcement with a release date.

Casting rumors

No casting announcements have been made for Sophie Foster or any main characters. Fan communities have speculated extensively, but speculation isn’t confirmation. The absence of casting news typically suggests the project is either in development limbo or the script phase hasn’t progressed to the point where character attachment makes sense. Until Disney confirms otherwise, every “Sophie Foster casting” rumor should be treated as fan fiction.

Keeper of the Lost Cities book 10 release date

As of 2025, Book 10 has not received a confirmed release date. Author Shannon Messenger has reportedly hinted at potential delays for the upcoming installment. The graphic novel adaptation has continued while the main series works through whatever is causing the gap, with Graphic Novel Part 2 releasing December 2, 2025 in the US and Canada.

Upcoming books

The series currently stands at 11 books with Book 10 still forthcoming. Book 8.5 Unlocked released November 17, 2021, and was named a Best Young Reader Book of 2020 by Barnes & Noble. The gap between Book 8.5 and the announcement of Book 10 delays spans several years — longer than typical gaps in this series.

Shannon Messenger’s official website and social media remain the most reliable channels for updates. The author has historically been communicative with fans about release timelines, even when those timelines shift. For readers tracking Book 10 specifically, watching for author announcements rather than retailer listings is the safest approach.

Series order

The complete series order for the main books runs from Book 1 through Book 9, with Book 9.5 (Unraveled) and the novella collection in between. A graphic novel adaptation of Book 1 is split across two parts, with both now available. This dual-format approach gives new readers an entry point that might feel more accessible than the 512-page original.

What this means: families can trust the core series details and reading recommendations while keeping expectations realistic for Book 10.

Keeper of the Lost Cities characters

The series features a rotating ensemble, but three characters consistently anchor the narrative. Sophie Foster sits at the center as protagonist, with Keefe Sencen and Fitz Vacker as her closest allies. Supporting characters come and go as the plot demands, but this core triangle drives most of the emotional stakes.

Sophie Foster

Sophie is the main protagonist — a twelve-year-old telepath who discovers she’s an elf from the Lost Cities. Her journey forms the spine of the series. Sophie’s defining trait is her struggle between secrecy and connection: her telepathy made her feel alien among humans, and joining the elvin world brought new challenges. She grows from frightened child to confident leader across the books, though that growth comes with significant costs.

Keefe Sencen

Keefe is Sophie’s closest friend, characterized by humor, loyalty, and a complicated family situation. He’s one of the most popular characters in the series — fan communities frequently cite Keefe as their favorite. His storyline in later books reportedly takes darker turns, exploring trauma and identity in ways that resonate strongly with teen readers.

Fitz Vacker

Fitz is Sophie’s other close friend, distinguished by his ability to read minds alongside Sophie’s telepathy. His relationship with Sophie has romantic undertones that develop across the series, though the books handle this with the careful pacing typical of middle-grade fantasy. Fitz’s family introduces political complications that create ongoing tension throughout the narrative.

Timeline

Key milestones in the series’ publication history and adaptation development:

The timeline shows a series that has maintained steady publication momentum while navigating the Hollywood development process. The 2021 film announcement briefly placed Keeper of the Lost Cities in mainstream entertainment coverage, but the subsequent silence suggests the project remains in uncertain territory.

Confirmed vs. unclear

Research confirms several facts about the series, though significant gaps remain around the most anticipated developments.

• Confirmed: Author Shannon Messenger has published 11 books in the series through Simon & Schuster, with the first debuting August 6, 2013.
• Confirmed: Sophie Foster is established as the telepathic protagonist throughout all main series entries.
• Confirmed: The series has sold over 2.5 million copies and achieved New York Times bestseller status.
• Unclear: Book 10 has no confirmed release date despite author acknowledgment of the project.
• Unclear: Disney film development status — Emma Watts’s role as director remains unverified.
• Unclear: No official casting announcements for any characters in the film adaptation.

What this means: families can trust the core series details and reading recommendations. For the film adaptation, expectations should remain cautious until Disney provides official updates.

What people are saying

The past and present unravel into staggering truths in this can’t-miss installment of the New York Times and USA TODAY bestselling Keeper of the Lost Cities series told entirely from Keefe’s point of view.

— Shannon Messenger, author

A Keeper of the Lost Cities live-action film adaptation was confirmed on January 11, 2021, with an article from Deadline, as well as Shannon Messenger’s Instagram and Twitter accounts.

— Keeper of the Lost Cities Wiki, fan community documentation

The dual engagement — from creator and audience — helps explain why the series has sustained popularity for over a decade.

Bottom line

Keeper of the Lost Cities delivers the fantasy adventure formula that middle-grade readers devour: a relatable protagonist with extraordinary abilities, a parallel world full of secrets, and stakes that escalate across eleven books. For parents wondering about age appropriateness, the official publisher rating (8–12) holds for early entries, though some review sources suggest 12+ for later books as themes deepen. The series has the sales trajectory and award recognition to back up its reputation.

For readers: the early books offer a strong starting point, with the graphic novel providing a potentially more accessible first encounter. Book 10 has no confirmed date, so families should enjoy the existing catalog rather than waiting for announcements.

For film hopefuls: Disney announced the project in 2021 with significant talent attached, but no confirmed timeline exists. Emma Watts’s current listing as director remains unverified, and casting announcements have not materialized. Treat film news as speculative until official confirmation arrives.

Related reading: Ben Affleck movies

Frequently asked questions