Book Review: Killer Instinct by Jennifer Lynn Barnes (Book 2 of The Naturals series)

by The Book Pup on March 8, 2026

Blurb for the book (on Goodreads):

Seventeen-year-old Cassie Hobbes has a gift for profiling people. Her talent has landed her a spot in an elite FBI program for teens with innate crime-solving abilities, and into some harrowing situations. After barely escaping a confrontation with an unbalanced killer obsessed with her mother's murder, Cassie hopes she and the rest of the team can get back to solving cold cases.

But when victims of a particularly brutal serial killer start turning up, the Naturals are pulled into an active case that strikes too close to home: the killer is a perfect fit for the profile Cassie has spent her whole life constructing of the man who murdered her mother.

The case gets even more complicated when the killer starts targeting the Naturals themselves. The closer Cassie gets to the truth, the deadlier the consequences—and the closer she comes to facing her mother's killer.

My Review

KILLER INSTINCT IS ABSOLUTELY SPLENDID! 🔥🔍

Jennifer Lynn Barnes took everything that worked in The Naturals and cranked it up to eleven. This sequel is SO MUCH BETTER than book one, and I'm genuinely thrilled about it! If you thought the first book was good, prepare to have your mind blown by this one. 🤯✨

Let me start by saying: this book is MORE ENTERTAINING in every way. The pacing is tighter, the stakes are higher, the danger feels more immediate, and I was absolutely glued to every page. Barnes doesn't waste time—she throws you right into the action and keeps the tension ramped up throughout. 💨

The plot twist! OH MY GOODNESS, THE PLOT TWIST! 😱 I'm not going to spoil anything because you NEED to experience it yourself, but let me just say I did NOT see it coming. Barnes sets it up perfectly, drops hints without making it obvious, and when the reveal happens, it's both shocking and completely satisfying. The kind of twist that makes you want to immediately reread the book to catch all the clues you missed. 🎯

What makes this book so intriguing is how personal it becomes. The case connects to Cassie's mother's murder, which raises the emotional stakes significantly. This isn't just another cold case—it's THE case that's haunted Cassie her entire life. Watching her navigate the investigation while dealing with the emotional weight of potentially facing her mother's killer adds incredible depth. 💔

The profiling and criminal psychology elements continue to be fascinating and well-researched. Barnes clearly knows her stuff, and the way the Naturals use their specific gifts to piece together the killer's profile and motivations is gripping. If you loved the profiling aspects in book one, you'll LOVE them even more here. 🧠

The character development is excellent! We get to know the Naturals even better—their relationships deepen, their dynamics shift, and everyone feels more three-dimensional. The Found Family vibes are stronger than ever, and watching them work together (and sometimes clash) while facing genuine danger made me so invested in all of them. 💕

The romance elements are woven in nicely without overtaking the thriller plot. There's development in relationships that feels natural and earned, adding emotional complexity without turning this into a romance-first story. The balance is perfect. 💫

Now, I'll be honest: there were some filler chapters scattered throughout. 📖 A few scenes that didn't quite advance the plot or add much to character development. Nothing major, and they didn't significantly slow down my enjoyment, but they're there. That's the only thing keeping this from a perfect 5 stars for me.

But overall? This book is REALLY ENTERTAINING, genuinely intriguing, and honestly just AMAZING. 🌟 Barnes has created a sequel that not only lives up to the first book but surpasses it in almost every way. The mystery is more complex, the danger more real, the emotional stakes higher, and the payoff incredibly satisfying.

If you read The Naturals and thought it was good but not amazing, PLEASE give this sequel a chance. It takes everything to the next level and delivers the kind of thriller that keeps you up way past your bedtime because you absolutely cannot stop reading. 📚💨

I'm already desperate for book three! Barnes has me completely hooked on this series, and I need to know what happens next RIGHT NOW. 🏃‍♀️✨

4.5/5 pawprints 🐾🐾🐾🐾 (so close to perfection!)

You can find the book on Goodreads here!

Who I think this book is for: Fans of The Naturals who want an even better sequel, readers who love criminal profiling and mystery thrillers, anyone who enjoys Found Family dynamics, and people who appreciate plot twists that actually surprise them.

Content warnings: Serial killer content, violence, murder investigations, emotional trauma related to past family tragedy, some disturbing crime scene descriptions

Reading order: Definitely read The Naturals first! This builds directly on book one and won't make sense as a standalone. (You can find my review for The Naturals here!)

Cheers, and happy reading (then immediately grabbing book 3)!

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