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The Delta Codex
Not yet published
Expected 14 Apr 26A girl whose subconscious contains dangerous ancient knowledge finds her voice in this gripping 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?
288 pages, Hardcover
Expected publication April 14, 2026
2 people are currently reading
88 people want to read
About the author
Deva Fagan
10 books212 followersI write fantasy and science fiction for readers of all ages. I live in Maine with my husband and our dog. When I'm not writing I spend my time reading, playing video games, doing geometry, and drinking copious amounts of tea.
NOTE: My comments on books I've read are not meant to be critical reviews, but are just my own reactions. I don't generally use stars, but I do occasionally mark a book with five stars if it's one that feels like it will become a long-term favorite, because it's exactly my sort of book, and caters to my specific tastes as a reader. There are plenty of books I read and really admire that are clearly excellent books, but which are not so exactly "for me" that I give them five stars. I will unabashedly stop reading books I really don't care for, so if a book is on my read list at all it means I liked it enough to finish it.
NOTE: My comments on books I've read are not meant to be critical reviews, but are just my own reactions. I don't generally use stars, but I do occasionally mark a book with five stars if it's one that feels like it will become a long-term favorite, because it's exactly my sort of book, and caters to my specific tastes as a reader. There are plenty of books I read and really admire that are clearly excellent books, but which are not so exactly "for me" that I give them five stars. I will unabashedly stop reading books I really don't care for, so if a book is on my read list at all it means I liked it enough to finish it.
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Displaying 1 - 8 of 8 reviews
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December 16, 2025My eighth middle grade novel will be out in April of 2026! The beautiful cover art is by James Firnhaber (https://www.jamesfirnhaber.com/ ).
The elements of this story have been with me for a long time, but only just came together a few years ago. I think my dedication for this book captures what it means to me:
To everyone raising their voice and speaking the truth, even when the world wants lies.
The elements of this story have been with me for a long time, but only just came together a few years ago. I think my dedication for this book captures what it means to me:
To everyone raising their voice and speaking the truth, even when the world wants lies.
Review of advance copy received from Netgalley
3.75 Stars Rounded Up
The Delta Codex by Deva Fagan delivers an imaginative sci-fi/fantasy that explores environmental issues with an emotional coming-of-age story. Set in the deceptive utopian city of Danak-Tol, the story draws you in with the intriguing premise of : children called codexes being chosen to be “honored” vessels for dangerous “echoes” of ancient knowledge.
Delta (main character) is a native and compliant protagonist whose loneliness and virtuousness shape the emotional core of the story. Her vow of silence creates a powerful sense of isolation, and the narrative does an excellent job of conveying her inner world without relying on spoken dialogue. As she begins to question the dynamics and leadership within the system she’s always trusted. She internally struggles between conforming to societal norms/laws and self exploration all within an increasingly dangerous environment.
The worldbuilding is one of the most interesting components within the story, because it’s imaginative and innovative filled with striking elements such as toxic blood storms, mechanical companions, strange wasteland creatures, and ruins of lost technologies. Each new setting feels treacherous and alive, reinforcing the sense that this planet holds far more secrets than its citizens are allowed to know.
One of the book’s greatest strengths is how it explores its central theme: the cost of restricted knowledge. Through Delta’s journey, the story asks thoughtful questions about truth, power, and whether knowledge itself is truly dangerous—or if control of it is the greater threat. Additionally, the relationships Delta forms along the way—especially with Flick—added much needed warmth and balance to Delta’s naivety and the darker elements of the story. Personally, one drawback was the pacing which occasionally slowed during exposition-heavy sections especially detailed environments, but the mystery surrounding the echoes and the world itself kept me wanting to read more.
Overall, The Delta Codex is a creative and thought-provoking debut that will appeal to readers who enjoy imaginative sci-fi worlds, heavily focused character journeys, and layered mysteries. It’s a story about belonging,, autonomy and the courage of seeking truth even when silence feels safer.
**this story may be more suitable for children on the higher end of the age range for middle grade**
A special thanks to Simon & Schuster Children’s Publishing, and NetGalley for the Advanced Reader’s Copy for review. My reviews always reflect my honest thoughts and feelings.
The Delta Codex by Deva Fagan delivers an imaginative sci-fi/fantasy that explores environmental issues with an emotional coming-of-age story. Set in the deceptive utopian city of Danak-Tol, the story draws you in with the intriguing premise of : children called codexes being chosen to be “honored” vessels for dangerous “echoes” of ancient knowledge.
Delta (main character) is a native and compliant protagonist whose loneliness and virtuousness shape the emotional core of the story. Her vow of silence creates a powerful sense of isolation, and the narrative does an excellent job of conveying her inner world without relying on spoken dialogue. As she begins to question the dynamics and leadership within the system she’s always trusted. She internally struggles between conforming to societal norms/laws and self exploration all within an increasingly dangerous environment.
The worldbuilding is one of the most interesting components within the story, because it’s imaginative and innovative filled with striking elements such as toxic blood storms, mechanical companions, strange wasteland creatures, and ruins of lost technologies. Each new setting feels treacherous and alive, reinforcing the sense that this planet holds far more secrets than its citizens are allowed to know.
One of the book’s greatest strengths is how it explores its central theme: the cost of restricted knowledge. Through Delta’s journey, the story asks thoughtful questions about truth, power, and whether knowledge itself is truly dangerous—or if control of it is the greater threat. Additionally, the relationships Delta forms along the way—especially with Flick—added much needed warmth and balance to Delta’s naivety and the darker elements of the story. Personally, one drawback was the pacing which occasionally slowed during exposition-heavy sections especially detailed environments, but the mystery surrounding the echoes and the world itself kept me wanting to read more.
Overall, The Delta Codex is a creative and thought-provoking debut that will appeal to readers who enjoy imaginative sci-fi worlds, heavily focused character journeys, and layered mysteries. It’s a story about belonging,, autonomy and the courage of seeking truth even when silence feels safer.
**this story may be more suitable for children on the higher end of the age range for middle grade**
A special thanks to Simon & Schuster Children’s Publishing, and NetGalley for the Advanced Reader’s Copy for review. My reviews always reflect my honest thoughts and feelings.
Review of advance copy received from Netgalley
3.5 stars, rounded up because it's an adventure that will be engaging for the target age audience (middle-grades readers). But that's also one of my concerns: this book is clearly written for middle-grades readers, but the content is pretty dark and heavy for that age group, imo (but not really straying into YA-specific themes). I think it would be a good fit for older middle-grades readers, but maybe if they know what to expect.
The overarching theme of anti-industrialization does get a little preachy, though not as bad as I've seen other places.
The writing style also didn't really work for me. The book is well written, but by necessity (due to world-building) there is a lot of description and very little dialogue, especially in the first half. For me, this makes the story drag some and feels like reading a narration of a story, rather than experiencing it. It's not quite as bad as some other books I've read (looking at you, Earthsea), but I personally didn't love it. Not sure younger readers will have any problem with it, though.
Thank you to the publisher and NetGalley for the digital ARC.
The overarching theme of anti-industrialization does get a little preachy, though not as bad as I've seen other places.
The writing style also didn't really work for me. The book is well written, but by necessity (due to world-building) there is a lot of description and very little dialogue, especially in the first half. For me, this makes the story drag some and feels like reading a narration of a story, rather than experiencing it. It's not quite as bad as some other books I've read (looking at you, Earthsea), but I personally didn't love it. Not sure younger readers will have any problem with it, though.
Thank you to the publisher and NetGalley for the digital ARC.
Review of advance copy received from Netgalley
This hyper-ambitious middle grade fantasy has stellar world-building, deeply poignant messages about the climate crisis and misinformation, and a phenomenal heroine in Delta. As she learns more about her life and as she and her ragtag crew take on corrupt politicians and impending storms, it is easy to root for Delta and feel inspired to do better in our world.
While this book is written for middle grade readers, I would recommend it more for middle school than upper elementary. The world-building is VERY complex, and I found myself getting confused at times. There are also some very deep and complex themes here, and it would benefit readers to either have more background in social studies or have an adult read with them. There is so much goodness here that I would not want readers to miss. I highlighted several lines that I want to keep for the future!
Thank you to NetGalley and Altheneum Books for Young Readers for an eARC in exchange for my honest review.
While this book is written for middle grade readers, I would recommend it more for middle school than upper elementary. The world-building is VERY complex, and I found myself getting confused at times. There are also some very deep and complex themes here, and it would benefit readers to either have more background in social studies or have an adult read with them. There is so much goodness here that I would not want readers to miss. I highlighted several lines that I want to keep for the future!
Thank you to NetGalley and Altheneum Books for Young Readers for an eARC in exchange for my honest review.
Review of advance copy received from Netgalley
Beautiful. I would give this 6 stars if I could.
The character development of the MC from the first chapter to the last is mind boggling. The world building? Even more so. This is one of the most unique worlds I've ever read. It was intricate and detailed and purposeful.
I loved all the characters except a select few that I wanted to toss from the book and tell them what for, but they weren't meant to be hated. They were meant to be seen as brainwashed by the corrupt government and absolute fear of a dying system.
The ending was perfect for the MC and for the world. When you read it, you'll understand because I can't spoil it! But for the storyline? Perfection.
Thank you to NetGalley for the E-Arc in exchange for an honest review.
The character development of the MC from the first chapter to the last is mind boggling. The world building? Even more so. This is one of the most unique worlds I've ever read. It was intricate and detailed and purposeful.
I loved all the characters except a select few that I wanted to toss from the book and tell them what for, but they weren't meant to be hated. They were meant to be seen as brainwashed by the corrupt government and absolute fear of a dying system.
The ending was perfect for the MC and for the world. When you read it, you'll understand because I can't spoil it! But for the storyline? Perfection.
Thank you to NetGalley for the E-Arc in exchange for an honest review.
October 22, 2025
ARC Copy...Actually on heavy side for middle grade which is good and even by the premise I really wanted to know what is the big secret is! Themes of ecology and censorship. It is obvious and uncomfortable to read through for a good reason that there is something wrong with Delta's world and her adult handlers , and not just the fact over how dehumanized Delta and her fellow Codexes are treated, which the codexes themselves don't seem to notice. So I was really happy once the secret was revealed cause now the heroes have to save the world before it comes crushing down literally.
Review of advance copy received from Edelweiss+
E ARC provided by Edelweiss Plus
Review of advance copy received from Author
A vividly engrossing story of terraforming gone askew, and the brave kids who fight to save their world. Excellent reading!
Displaying 1 - 8 of 8 reviews