The Delta Codex
Published on 14. April 2026
Book
Hardback
288 pages
978-1-6659-6357-2 (ISBN)
Description
A girl whose subconscious contains dangerous ancient knowledge finds her voice in this "gripping...emotionally resonant" (School Library Journal, starred review) middle grade sci-fi fantasy perfect for fans of Diana Wynne Jones and Scott Reintgen.
Is there safety in silence?
In the city of Danak-Tol, children known as codexes are chosen to safeguard echoes-fragments of ancient knowledge too valuable to destroy but too dangerous to use. Forbidden to speak lest she accidentally release her echo, codex Delta lives a lonely life. Still, she knows she must obey the wardens' strict rules to keep her home safe from the vicious beasts, heretical Scrappers, and toxic blood storms that lurk beyond the city walls.
But when Delta breaks her vows to help a young girl escape a blood storm, she begins to have strange dreams, which lead her to question everything she knows to be true about herself and her city. To find answers, Delta must journey to the one place she most fears: the wasteland beyond the walls of Danak-Tol.
Together with her small but feisty mechanical companion Flick, Delta dares the perilous ruins of a long-abandoned skyship, the gullet of a ravenous sphincter worm, and even befriends a young Scrapper named Drii. But all these adventures only lead to more questions. What is the true danger that threatens her entire planet-is it really her echo, or is it the silence that has imprisoned the truth for so long?
Is there safety in silence?
In the city of Danak-Tol, children known as codexes are chosen to safeguard echoes-fragments of ancient knowledge too valuable to destroy but too dangerous to use. Forbidden to speak lest she accidentally release her echo, codex Delta lives a lonely life. Still, she knows she must obey the wardens' strict rules to keep her home safe from the vicious beasts, heretical Scrappers, and toxic blood storms that lurk beyond the city walls.
But when Delta breaks her vows to help a young girl escape a blood storm, she begins to have strange dreams, which lead her to question everything she knows to be true about herself and her city. To find answers, Delta must journey to the one place she most fears: the wasteland beyond the walls of Danak-Tol.
Together with her small but feisty mechanical companion Flick, Delta dares the perilous ruins of a long-abandoned skyship, the gullet of a ravenous sphincter worm, and even befriends a young Scrapper named Drii. But all these adventures only lead to more questions. What is the true danger that threatens her entire planet-is it really her echo, or is it the silence that has imprisoned the truth for so long?
Reviews / Votes
* "In this gripping science fiction thriller, Fagan reiterates her strength as a masterful world builder. . . . Fans of Scott Reintgen and Fagan's earlier works will eagerly embrace this thought-provoking, emotionally resonant novel." -- School Library Journal, starred review "Delta's journey from parroting propaganda to thinking for herself is the kind of compelling and believable that has brought decades of readers to Lois Lowry's The Giver and newer generations to Donna Barba Higuera's Alebrijes." -- Shelf Awareness "Readers will be drawn in by the warm, wholesome cast of characters. A hopeful, exciting, and action-packed adventure." -- Kirkus "[E]lectric . . . . Concise, economical storytelling and steady pacing mold a vast dystopian world whose charismatic leads evoke protective warmth from the jump." -- Publishers Weekly "It's an exquisitely crafted sci-fi mystery, and though suspense and action abound, it makes time for humorous asides and moments of wonder. An extensive history and mythology flesh out the fascinating world, and Delta's internal journey feels as profound as her external odyssey. An exhilarating examination of the power of stories, truth, and kindness." -- Booklist "A unique setting with an intriguing history, a dystopian society of secrets and hierarchies, and a tween learning on the fly just how bold she can be-there's a lot here to recommend to sci-fi fans." -- BCCB "From the intriguing premise to the rapidly unspooling mystery of the bloodstorms and how they relate to the Founders, Fagan keeps things moving in this energetic sci-fi tale, where every ally Delta makes takes her one step closer to understanding what has been placed in her head. The stakes get higher throughout, so that by the end planetary survival is on the line and the deceit has been stripped from every bastion Delta's life is founded on, leaving her the better for it." -- The Horn Book MagazineMore details
Language
English
Place of publication
New York
United States
Publishing group
Simon & Schuster
Target group
Children/juvenile
US School Grade: Fifth Grade and over, Interest Age: From 10 to 99 years
Product notice
sewn/stitched
Cloth over boards
Illustrations
f-c jkt (uncoated: fx: emboss, spot gloss UV); digital
Dimensions
Height: 215 mm
Width: 147 mm
Thickness: 33 mm
Weight
350 gr
ISBN-13
978-1-6659-6357-2 (9781665963572)
Copyright in bibliographic data and cover images is held by Nielsen Book Services Limited or by the publishers or by their respective licensors: all rights reserved.
Schweitzer Classification
Other editions
Additional editions
Deva Fagan
The Delta Codex
E-Book
04/2026
Atheneum Books for Young Readers
€10.87
Available for download
Person
Deva Fagan writes fantasy and science fiction for all ages. When she's not writing, she spends her time reading, doing geometry, playing video games, hiking, and drinking copious amounts of tea. She is the author of several books, including Rival Magic, Nightingale, The Mirrorwood, A Game of Noctis, and The Delta Codex. She lives in Maine with her husband and their dog. You can find her online at DevaFagan.com.