Unbound: Tethers hold. Until they break.

by Brian Moyer

Esah survived Splinter—barely. Now he's back at Delaney Rim carrying three simple capabilities at once, a thing that should have killed him. Air. Spark. Navigation that turns out to be earth. Three foundations layered into one mind, all of them refusing to compound. By every rule of the world he splintered into, he should be at the bottom—bound to a fifty-mile range, useless for trade, fit only to be caged or culled.

Instead he's free.

Back at Barrel Springs, the small community that took him in his first season—Hoda the anthropologist, Huutsuu the engineer who lost everything in the transfer, Ama who can pull clean water out of poisoned ground, and the rest of the people who taught him to live in the basin—begins something new. A teaching camp at the rim. Foundation work. Real instruction. The basics the territories have spent a generation hoarding. People come. People learn. People stay.

The territories notice.

For four hundred miles in every direction, an Authority decides who gets to develop a capability, who gets to travel, who counts as a person. The basin doesn't just trap the rain and snow that fall into it—the basin splinters are also trapped, by their tethers. A teaching camp at the rim is not a settlement. It is a fracture. And fractures spread.

What Esah and the people of Barrel Springs are about to learn is older than the territories, older than the splintering, written into the geography itself. What they do with that knowledge will decide whether the rim becomes a refuge or a target.

Unbound is the second book in the Splintered World science-fantasy series. The rules Esah learned in Splinter were the easy ones. The ones that come next are written in fire—and the empire that wrote them is starting to crack.

The series Unbound launches in print and audiobook simultaneously, performed by Luke Daniels—Audie Award winner with over 1,000 titles narrated, including The Three-Body Problem and the Iron Druid Chronicles.

387 pages, Kindle Edition

Published August 2, 2026

Reviews

[S.J. Higbee]

As Unbound picks up more or less immediately from the end of the first book, my recommendation is that whatever you do, don’t pluck this one off the shelves until you’ve had the pleasure of reading Splinter. We are immediately plunged back into the adventures featuring the same characters that starred in the first book, which I enjoyed. It can be off-putting to be confronted with a new cast, especially while in the throes of lots of action and Moyer doesn’t pull this stunt with his readers.

This time, the stakes are no less high but different as we begin to see the world outside Barrel Springs Basin, where our plucky protagonists have been corralled. Pages flew by as I learned more about how this wider world worked. Once again, I was impressed at the immersive writing that had me smelling and tasting the desert, clearly benefitting from Moyer’s deep knowledge and love of the area. The characterisation is also very well done. We get to see Esah’s weaknesses, as well as his strengths in this unsentimental treatment of Moyer’s main protagonist, which had me completely in his corner.

I particularly enjoyed how Moyer took the first slice of the story in Splinter and enlarged it, both literally and figuratively. I got to learn how much bigger the world is outside the desert territory and how the rules have been changed to suit certain people. The build-up to the inevitable showdown is very well done and had me reading far later than I’d planned to discover what happens next.

Any niggles? Moyer’s knowledge of the region runs deep – he doesn’t just have a strong appreciation of the landscape and harsh conditions, he also knows a great deal about the water courses and geology. While I understand the reader needs to appreciate some of the information he imparts, I did feel he went down something of a rabbit hole where there was far more detail than the story required. So I did skim a fair amount of that stuff. However, it wasn’t a dealbreaker and there is so much about this world and the premise that I’ve thoroughly enjoyed, that doesn’t prevent me from strongly recommending the book to fans of portal fantasy adventures – especially if you appreciate something a bit different. I’m eagerly awaiting the next book in the series, which is due to be released on 1st September.
9/10

[Dani]

Thank you to NetGalley for the opportunity to read this advance copy.

After loving Splinter, I couldn’t wait to return to Brian Moyer’s richly imagined world, and Unbound delivers everything I hoped for. The world-building continues to expand beautifully, revealing more of the mysteries introduced in the first book while creating plenty of new questions to keep me invested.

Esah’s journey becomes even more compelling as he learns more about his abilities and his place in this world. The supporting characters also continue to develop, with their relationships bringing real emotional depth alongside the action and tension.

The pacing is excellent, balancing quieter character moments with escalating stakes and gripping twists. By the final chapters, I was completely hooked and couldn’t turn the pages quickly enough.

This series continues to go from strength to strength. Imaginative, engaging and filled with characters I genuinely care about, Unbound has left me eagerly awaiting the next instalment. Highly recommended.

[Nancy Tice]

I have had another delightful experience devouring the second book in The Splintered World Series by Brian Moyer. Thanks to the Author and Net Galley for being able to read this early. I usually start reading with some degree of trepidation when I sincerely loved a first book in a series. There have been too many times that been disappointed and an author simply couldn’t keep the fun and excitement going.
However, happy to report that this was not the case. Once more, I was engrossed and fascinated by this continued tale of an imagined alternate earth. Many characters from Book One were fleshed out, more traveling in this strangely captivating landscape, and other players made their appearances.

As a person from the Northeast, I loved reading about such a gorgeous setting so different from what I am accustomed to.
I look forward to seeing more of these characters and watching them and their world evolve.
I never dreamed that a book I loved could make me wish I had paid a bit more attention to chemistry class in high school. You’ll see…

[EmJ]

This is the second book in the Splintered. It's going to be hard to write this review without giving away spoilers. I'm really enjoying this series. The world building continues to be complex and based on actual science. There was good character and relationship development in this story. I actually liked that focus was split between Esah and some of the other characters. The suspense that drives this story forward is due to the mystery Esah, Hoda, ect are trying to solve. Overall the pacing of the story was good and the writing style moved the story forward. I would consider this more of a cerebral sci-fi series. I look forward to seeing where the story goes and what happens now that they've started to figure things out. I also need to see how Hoda deals with things. If you've read the book you know what I'm talking about.

Thank you to the author for the ARC in exchange for my honest review.

[Henry Lazarus]

Brian Moyer continues the tale started in Splinter(ebook) which introduced a world that people fall into. Esah has integrated the three talents he got in the first tale and he and his friends have drawn the attention of three organized groups that are looking for the reason why more people have been splintering into this part of Wyoming and also have to become Unbound(ebook) from the tether that limits the distance one can travel from their splinter point. I’m enjoying this survival with magical talents series. According to Brian’s website there are four more books already written and coming out one a month. I’m hooked.

[Emily (The Litertarian)]

This second installment in the Splintered World series maintained its intrigue, but for me, it leaned too far into technical territory to be as immersive as I'd like. There was plenty of drama, but I felt like the majority of time was spent in the nitty-gritty details of the talents in a way that became a little trying for me. Thematically though, this was a winner. Teamwork and unity in a place that is essentially survival of the fittest worked so well. There are several more books slated in this series, and I can't wait to see where it goes next!

[Dark Reader]

This is the second book in the Splintered World series, and you should definitely start with the first book, Splinter. I really enjoyed Splinter, and Unbound delivers on the things I loved about it. The world-building becomes even more complete, and we learn more about many of the characters as well. It's hard to give too many details without delving into spoiler territory here, but this journey to an alternate world was definitely a good one. I can't wait to see what's next!

[Lucy F.]

want more. couldn’t stop reading

This series is fast moving and full of likeable characters. The establishment of alternate universe was handled well. I’ll read the next in the series for sure.

[Deborah Svensson]

This is a great story in a fascinating series! I eagerly await Tethered coming out September 1, 2026!