In a world where every child bonds with a spiritual guide, some promising greatness and glory and others bringing destruction and death, the fates of young teens Mako and Arden collide, and together they must contend with bandit armies and dangerous secrets to fight an enemy who could destroy all they’ve ever known.

Such is the premise of Guardians: Forbidden Mountain, the debut novel of a fantasy series by Brandon Mull, announced by Liesa Abrams, VP and editor-in-chief of Labyrinth Road, an imprint of Random House Children’s Books. The book will be released on April 7, 2026 as a deluxe first edition hardcover featuring sprayed edges and a 125,000-copy first printing.

Showcased here for the first time is the novel’s cover, featuring art by Japanese illustrator Yuta Onoda and designed by Katrina Damkoehler, RHCB associate director of art and design.

The publisher also disclosed that, as of next April, Labyrinth Road will become home to the author’s Fablehaven and Dragonwatch paperbacks, originally released by Shadow Mountain. Mull made his publishing debut with Fablehaven, which has sold more than 3.5 million copies worldwide since its 2006 launch. Timed to coincide with the series’ 20th anniversary, a film adaptation of Fablehaven, produced and distributed by Angel Studios, will be released next year.

Asked about the genesis of Guardians, Mull told PW that he has long wanted “to create a fantasy series that involved the spiritual aspects of life in a way that would feel magical and exciting. The novels will be grander and more epic than my Fablehaven novels, and will hit some levels of intensity that are on the older side of middle grade.”

For Abrams, who acquired and edits Guardians, the series marks the second chapter of her work relationship with Mull, whose earlier books she edited during her tenure at Simon & Schuster. “I edited Brandon’s Beyonders and Five Kingdoms series when Aladdin published the paperback editions,” she explained. “I also co-edited his Dragonwatch series alongside the Shadow Mountain team, which published the hardcover editions of those books, and Aladdin published the paperbacks while I was there.”

Abrams welcomed the chance to reunite with Mull to publish what she described as “his most ambitious and expansive series yet.” Noting that Guardians is the author’s “first entirely second-world fantasy series,” since his previous series were either set in the real world, or set in fantasy worlds into which real-world protagonists enter, she added, “Brandon here brings his incredible talent for unique world-building to the next level, while still focusing on the universe questions and exciting action that have appeared in all his books.”

Behind the Cover

Designer Damkoehler had a vision for Forbidden Mountain’s cover early on. After reading an initial draft of the manuscript, she recalled, “Brandon’s vivid descriptions of hero Mako’s mountain home really stood out to me, as did how the settings dwarfed the people in the story. I felt like Mako might also feel a bit dwarfed by all his dreams and the unknowns of figuring out who he is supposed to be and how to make a difference in the world. I wanted the reader to get a sense of how big and powerful both the mountain setting and Mako’s chosen guardian might feel to him—but also make sure we get a sense that Mako is special and can face difficult trials.”

Damkoehler also had a strong hunch about which illustrator could bring these visual concepts to life. “I’ve been a fan of Yuta Onoda’s cover illustrations for a long time,” she said of the Tokyo-based artist. “He is able to capture fantastical and sweeping settings with a level of detail that makes me want to look closer and makes me believe they could be real places. I love how Yuta was able to give us a hint of Mako’s mindset with this cover art—Mako idealizes his guardian, sees a great warrior, and tries to imitate his guardian's pose of strength—but he is still a kid and still has some human vulnerability.”

Mull praised Onoda’s Forbidden Mountain cover art for “handling nicely Mako’s partnership with a dangerous spiritual guardian who will mentor and influence him.”

The cover captures elements of Mull’s goal, with Guardians, of building “a world that makes the spiritual dimension of life feel powerful and magical, and to tell a story where the main character had a distinct inner battle to complement his outward challenges.” The series, the author said, “will only span three novels, but each will be longer than normal for me, packed with a lot of adventures and surprises. I have been planning this story for more than 10 years, and if I have a masterpiece in me, this will be it.”

Guardians: Forbidden Mountain by Brandon Mull. Labyrinth Road, $19.99 Apr. 7, 2026 ISBN 978-0-593-71204-7