Book Review: All In by Jennifer Lynn Barnes (Book 3 of The Naturals series)

by The Book Pup on May 1, 2026

Blurb for the book (on Goodreads):

Three casinos. Three bodies. Three days.

After a string of brutal murders in Las Vegas, Cassie Hobbes and the Naturals are called in to investigate. But even with the team's unique profiling talents, these murders seem baffling: unlike many serial killers, this one uses different methods every time. All of the victims were killed in public, yet the killer does not show up on any tape. And each victim has a string of numbers tattooed on their wrist. Hidden in the numbers is a code—and the closer the Naturals come to unraveling the mystery, the more perilous the case becomes.

Meanwhile, Cassie is dealing with an equally dangerous and much more painful mystery. For the first time in years, there's been a break in her mother's case. As personal issues and tensions between the team mount, Cassie and the Naturals will be faced with impossible odds—and impossible choices.

My Review

All In continues The Naturals series with an intriguing mystery that showcases Jennifer Lynn Barnes's skill at crafting complex cases. While it didn't quite reach the heights of Killer Instinct for me, it's still a solid addition to the series. 🔍📚

Let me start with what I absolutely LOVED: the complexity of this mystery! 🧩✨ The Fibonacci sequence integration and everything related to the case was SO well thought out and planned. Barnes clearly put a lot of work into making this mystery intricate and intellectually satisfying. The mathematical patterns, the way the clues build on each other, the complexity of the killer's game—it's all impressively crafted.

As someone who appreciates when authors really think through their mysteries, I was genuinely impressed by how layered this case is. The Fibonacci sequence isn't just slapped on as a gimmick, it's woven throughout the investigation in clever ways that make you appreciate Barnes's planning and attention to detail.

The profiling elements continue to be fascinating! Watching the Naturals use their specific gifts to decode the patterns and predict the killer's moves is engaging, and Barnes knows how to make the criminal psychology aspects compelling. 🧠

However, after reading Killer Instinct which was AMAZING and action-packed, this book felt like a bit of a step down in terms of pacing and excitement. 📖

It wasn't as action-filled as book 2. ⚔️ There are definitely tense moments and dangerous situations, but the energy level feels lower compared to the previous installment. More time is spent on decoding clues and analyzing patterns than on high-stakes action sequences. If you're coming off the adrenaline rush of book 2, the pacing here might feel slower.

The book was also a little sad. 😢 Without going into spoilers, there are some emotional and heavy moments that give this installment a more melancholy tone. It's not a bad thing necessarily—it adds depth and shows consequences—but it does make the reading experience feel heavier than the previous books.

The ending was a little confusing. 🤔 After all that complex buildup with the Fibonacci sequence and intricate clues, the resolution didn't feel as clear-cut as I would have liked. I finished with some lingering questions about certain plot points and character motivations. It's not completely unsatisfying, but it could have been tighter and clearer.

The mystery itself, while intellectually complex and well-planned, doesn't have quite the same emotional punch as the case in Killer Instinct. That book felt personal and urgent in a way that this one doesn't quite match, despite the fact that the Naturals are being targeted. 💔

The pacing is also more uneven here. Some sections move quickly and keep you engaged, while others feel slower as the team works through the mathematical patterns and clues. If you're not as interested in the Fibonacci sequence aspects, those sections might drag a bit. ⏰

That said, all in all, it was good! Barnes continues to write compelling mysteries with smart characters and intricate plotting. Even if this wasn't my favorite in the series, it's still an entertaining read that advances the overall story and character arcs. The complexity of the case shows Barnes's skill as a mystery writer, and there are definitely moments that had me hooked. ✨

If you've made it this far in The Naturals series, you should absolutely continue with this one. Just know that it has a different tone than book 2—less action-packed, more emotionally heavy, and more focused on puzzle-solving than adrenaline-pumping danger. 📚

I'm still invested in this series and will definitely continue to book 4! Barnes has created a world and characters I care about, even if not every installment hits the same high notes. 💫

3/5 pawprints 🐾🐾🐾

You can find the book on Goodreads here!

Who I think this book is for: Fans of The Naturals series (obviously!), readers who love mathematically complex mysteries, anyone who appreciates intricate puzzle-solving over constant action, and people who don't mind a more emotionally heavy tone.

Content warnings: Serial killer content, violence, emotional/heavy themes, deaths (no specifics to avoid spoilers)

Reading order: Definitely read The Naturals and Killer Instinct first! This builds directly on previous books and won't work as a standalone. (You can find my reviews for The Naturals and Killer Instinct on my blog!)

Cheers, and happy reading!

The Book Pup

P.S. That Fibonacci sequence complexity though, major props to Barnes for the planning and execution! 🔢✨