This book was very entertaining. It is about a unit inside the FBI called Patterns and Recognition (PAR). Gardner Camden is part of that unit. He is, I thought, on the spectrum but a genius at puzzle solving. So that being said he can crack some cases that the FBI have problems with. The story is about a serial killer killing other serial killers. One of those killed serial killers was thought to be dead seven years ago. But because of DNA they do realize that he was alive and hiding out until he was killed by the "serial killer". The serial killer seems to always be one step ahead of PAR which is another puzzle in itself. There are some twists and turns in this book but not anything that wasn't believable. It was a great read with some really awesome characters who were very well developed throughout the story. If you are a John Sandford or Michael Connelly fan you will definitely enjoy this read.
Thanks to #netgalley, #minotaurbooks and @johnmcmahonbooks for an ARC of this great read. All opinions are my own.

📚 #BOOKREVIEW 📚
Head Cases (PAR Unit, Book 1) by John McMahon
⭐️⭐️⭐️⭐️ / Pages: 352 / Genre: Police Procedural
Release Date: January 28, 2025

FBI Agent Gardner Camden is an analytical genius when it comes to solving crimes and puzzles but a complete noob when it comes to interacting with people. He’s part of the Patterns and Recognition (PAR) unit, which also includes a mathematician, a weapons expert, and a computer analyst. In this first book of the series, DNA of a dead serial killer turns up at a murder scene, which then leads to more clues specifically made for Gardner. Can he figure out who’s responsible before it’s too late?

I enjoyed this thriller and the characters in it. I know I’d hate dealing with someone like Gardner in real life, but for some reason I really like reading about them. I’ll be keeping an eye out for this series.

Thank you, @JohnMcMahonBooks, @StMartinsPress, and @NetGalley for my gifted copy.

PAR or Patterns and Recognition is a special unit within the FBI. It consists of four agents and one supervisor. The agents all have special talents and blemished personnel files. Normally they never leave their office in Jacksonville, but when an old case is reopened they’re sent out into the field. A serial killer’s body who they thought had died in a home fire years ago suddenly turns up in Texas.
A thrilling whodunit with a likable protagonist and riveting plot. Gardner Camden, who is tasked to lead the investigation, is socially inept but a total whiz when it comes to figuring out patterns and solving puzzles. I like how he’s aware of his shortcomings and works to overcome them. He shows a lot of personal growth as the story progresses. He’s got a great team around him and they have each other’s backs. The plot has some twists and turns to ratchet up the suspense level as well. It’s a good story. 4.25 stars

Let's hear it for the dad fiction (what my husband calls this)! It's the start of a new series of what seems to be a police procedural, but FBI.

FBI Agent Gardener Camden is neuroatypical. He works in a division of misfits to solve the puzzles of investigations. A serial killer has re-emerged and they are on the case. I did enjoy this book and look forward to following the series. I would have liked more on all of the character, but maybe that is coming later in the series.

Thank you to NetGalley and Minotaur Books/St. Martin's Press for an advance copy for my honest review.

Remember the golden era of Criminal Minds? Head Cases gave me such nostalgic vibes reminding me of the best parts of the show. So naturally I couldn’t put it down! Simply inhaled it within 24 hours! And yes, definitely a binge worthy story.

An FBI team consisting of exceptional “oddballs” on a hunt for a Dexter style serial killer? Sign me up immediately. Am I already obsessed with Gardner Camden, the neurospicy main character? You know it! As someone whose brain does not function in the same way as what’s considered “neurotypical”, I love reading about “neuroatypical” characters. I especially loved other characters described through Gardner’s eyes and details he focused on.

The red herrings along the way were great. As were the twists! But more than anything it was the characters that made me so invested in the story. I’m so glad I read the author’s at the end and found out book 2 is already in the works. I’m definitely committed to this series and hoping there’ll be many many more books in it!

A huge thank you to Minotaur Books for my ARC and to John McMahon for writing it!

Great start to a new series. I appreciate so much having a neurospicy MC whose story is not all about his neurodivergence - it's just one facet of who he is. The characters were developed well, and the relationship between the MC and his partner is great. I love her character as well and their interactions feel genuine. I think McMahon did a great job of not giving away the story too soon and saving a few twists for the end. I will say - this is not for the faint of heart or stomach! I will definitely look forward to the next book in the series and plan to go back and read his other books as well.

4.5 stars

"Head Cases" by John McMahon is a new, yet different kind of, police procedural that keeps you on the edge of your seat from start to finish. The plot had many twists and turns [literally and figuratively], making it both exhausting (poor Gardner just couldn't stop traveling) and a real page-turner. McMahon’s characters are well-developed and relatable, adding depth to the story. While some parts may feel a bit predictable, the overall experience is highly enjoyable and satisfying.

A great read for fans of murder and police dramas - I'm very excited to see what comes next for the PAR.

Thank you to St. Marten's Press for my copy of HEAD CASES. This one is out Jan 28.

I really wanted to like this one but it was just so sterile and not at all interesting. I didn't really care about any of the characters and it was hard to stay connected to this story. I don't recommend this one.

Agent Camden is part of a small group of FBI agents in the PAR department. They handle cases that no one else can solve and have exceptional qualities at solving riddles and seeing patterns that other agents can’t. The team is dispatched to Texas, where a serial killer has been murdered. While investigating that crime another serial killer is murdered. What ensues is a cat and mouse game between Camden and the killer. This is your usual run of the mill police procedural concept. What I was hoping for was a bit more grit to it. I felt the characters were too one dimensional and I didn’t feel any attachments to them. They were just “ characters in a story.” The crime itself definitely had interesting aspects to it but again didn’t get into that dark, gritty type of book I enjoy, however I do believe anyone who enjoys a police procedural without getting too graphic this would certainly like this one.

Thanks to NetGalley and the publisher for my ARC in exchange for an honest review.

The ultra braniac, best problem solvers but a little socially inept FBI agents are in one department that everyone else jokingly calls "Head Cases". Each one has unique talents but also had an issue that landed them in the PAR department. When DNA leads to a serial killer declared dead long ago and other criminals are being murdered, the PAR unit is tasked with finding out who is seeking vigilante justice, how/if they are related and why. If you love puzzles, you will love this book and how they put the pieces together. Can't wait for the next book about these amazingly talented FBI agents!

Thank you to St. Martin's Press and NetGalley for the ARC!

John McMahon’s Head Cases is a brilliant start to what I hope will be a long-running series featuring the FBI’s Patterns and Recognition (PAR) unit. With its razor-sharp puzzles, dynamic team dynamics, and heart-pounding suspense, this book is impossible to put down. I devoured it in record time and am already eagerly awaiting the next installment—though I’m almost sad I read this one so early, knowing the wait for the sequel may be long.

At the center of the story is Gardner Camden, a genius investigator with a remarkable talent for solving puzzles, but a frustrating inability to connect with people, including his young daughter, Camila. As part of the quirky and highly specialized PAR team, Gardner dives into an investigation that’s as chilling as it is intricate. DNA evidence linking a murder victim to a long-presumed-dead serial killer sets off a series of twists, turning the hunt for the killer into a deadly game of cat and mouse.

McMahon excels at creating complex characters, and the PAR team is no exception. Each member, from the mathematician to the computer analyst to their no-nonsense leader, adds depth and personality to the story, making the team feel like a family of misfits with unparalleled talent. The riddles and patterns the team deciphers are not only intellectually satisfying but also integral to the emotional stakes of the plot.

The audiobook, courtesy of Macmillan Audio, takes the experience to another level. The narrator perfectly captures the nuances of Gardner’s analytical mind, the banter between the team members, and the tension of their race against time. Each character is distinct, making it easy to follow the ensemble cast, and the narration brings the book’s puzzles and high-stakes action to life.

I’m deeply grateful to St. Martin’s Press for granting me access to the book via NetGalley and to Macmillan Audio for the audiobook. Both formats are phenomenal and equally engaging, and I highly recommend them to fans of intricate, character-driven mysteries.

Head Cases is a triumph of intellect, suspense, and heart. McMahon has crafted a series debut that feels fresh and engaging, with a case that is as clever as it is thrilling. If you’re a fan of ensemble casts, intricate puzzles, and high-stakes thrillers, don’t miss this one. And like me, be prepared to count down the days until the next book in the series!

This gripping debut features FBI agent Gardner Camden, an expert at puzzle-solving, and his colleagues in the Patterns and Recognition (“PAR”) Unit, a sort of A-Team of misfit agents each exceptional at some particular skill—computers, olympic-caliber precision shooting, math, etc. This premise feels like one of those TV shows in which a motley team of crime-fighters uses its diverse skills to catch the bad guys, but there’s a reason those shows are fun. Who doesn't love a socially inept, crime-solving genius with a solid group of talented teammates? Here the group is on the trail of a killer targeting serial killers. Fortunately, the relentless drama and action are focused on the chase from the point of view of the good guys (sort of like a thriller meets procedural), without the currently fashionable but gruesome tendency to focus on the criminals or their point of view. For the agents in PAR, there’s not much sleep and a lot of flying around the country trying to beat the bad guy to the punch. Meanwhile, the team members all have their own quirks as well as career mistakes that caused them to get assigned to this squad, which may or may not be targeted by the higher-ups for the chopping block. All of this makes for a compelling story that I hope is the beginning of a series.

Thanks to Netgalley and St. Martin’s Press/Minotaur Boks for a digital advance review copy.

⭐️⭐️⭐️
I had mixed feelings about this book. Most of it was slow, and I struggled to stay engaged for the first two-thirds. However, the pace picked up at the end, going fast and furious, which I enjoyed. The ending was good, though not surprising.

I’ve heard people compare this book to Criminal Minds, but I didn’t get that vibe. Maybe I’m an outlier, but it lacked the emotional depth and team dynamics I expected.

Gardner Camden is an interesting lead—analytical and focused—but felt a bit one-dimensional. The PAR team had potential, but I wish they were explored more. The riddles and puzzles were a nice touch, but not as impactful as I’d hoped.

It wasn’t bad, but it didn’t grab me until the end. Fans of procedural thrillers with lots of logic might enjoy it more than I did.

Thank you, NetGalley, Macmillan Audio, and St. Martin’s Press, for the e-ARC and audiobook in exchange for my honest review!

This was such a strong start to a new series, if you’re a fan of Criminal Minds or other shows like that this was excellent! This follows an FBI team of misfits called PAR as they race to solve a complex and tricky case. I really liked that the team wasn’t a bunch of super agents with stellar records, instead they’re made of up individuals who toe the line and have some behavioral issues and quirky tendencies. The concept of a serial killer hunting other serial killers was fantastic and lent to a fast paced and exciting ride. The characters were well developed, the case was complex and twisty and the entire thing was gripping, definitely recommended!

FBI Agent Gardner Camden and his team in the Patterns and Recognitions Unit (PAR) are assigned a new case. With two former serial killers dead, they have to figure out who is killing them and need to do it fast. It is not only their careers at stake, but so is the image of the FBI at stake. When the serial killer killer begins to taunt Gardner, he becomes more determined to figure out who it is, and he’s got an idea of where he just may find the suspect.

I REALLY enjoyed this book. It was sort of like reading a criminal minds type book but not exactly. It was less about profiling (but there is a bit of that in there), and more about following the evidence and using the skilled thinking of a trained agent to know where to assign his team to look for clues and information.

McMahon wrote such great characters that really came alive in this book. Each of them had a distinctive voice and skill, each of them had a purpose. This was the perfect team. I especially loved the working professional relationship between Gardner and Cassie; they seemed to be able to tell what the other was thinking and had a non verbal way of communicating.

While there are many books about serial killers, and I have read books about someone killing serial killers, this one didn’t feel like anything that I had read before. The precise way that McMahon commanded the interactions of the Agents made this feel very real. This is definitely a book that could be made into a TV series.

I can see this book being enjoyed by many!!!

FANTASTIC! Loved this. Twisty and turns roller coaster ride. So glad this has a second book planned. This was a plot driven story told from the perspective of the man leading the team. Camden Gardner is part of a newer team within the FBI that focuses on patterns. They are on the path of a serial killer taking out serial killers. I would love to learn more about the other members of the team in future books?!?!

Unputdownable! A twisty FBI procedural that has the fun sneaky feels of a cat and mouse game; the cat.. serial killer, the mice.. FBI agent Gardner Camden and the FBI PAR Unit tracking him/her. When the body of a serial killer known to be long dead is found, and then a second body with the same M.O. is also recovered, the team jumps into action to find the serial killer behind these and other murders happening around the country. I love how this puts me in mind of my favorite show, Criminal Minds, which is comprised of quick-smart agents that solve the unsolvable. I’m fangirling over Gardner.. quirky, neurodivergent?.. + ALWAYS does what’s right, even sacrificing to do it. You personally get to know each character as McMahon skillfully brings them to life on page. The killer literally plans his conquests as part of a “puzzle,” so lots of suspense here. Without giving away the ending let’s just say it was marvelous!! You shouldn’t let this pass you by! 5 stars — Pub. 1/28/25
*new to me author

Thanks to St. Martin’s Press for this complimentary copy. All opinions are my own.

NetGalley Review

Head Cases by John McMahon

⭐️⭐️⭐️⭐️⭐️

Pub Date: 01.28.25


First things first, thank you to NetGalley and Minotaur Books for the advanced readers copy- all opinions are my own.


This book red like as if Dexter and Criminal Minds had a baby. I absolutely loved the main character, and although he was a little quirky at times, his quirkiness wasn’t shoved in your face.

having a father with Asperger’s, I absolutely love reading about books that remind me about him and this main character reminded me about him. He had a thing with patterns and that’s totally my father.

When I am reading crime book/thrillers, I am always super picky and harsh about how the investigation goes down and I felt like this one was pretty accurate to how an investigation will go down in real life, although there were some over-the-top scenes regarding FBI stuff- I also am not a person that is in the FBI so I don’t know if that is realistic or not. It just seemed like there were some things that might not be really how they’d deal with a situation.

Although I felt that the side characters could’ve been a little bit more flushed out maybe McMahon has plans to do that in the following books which I am looking forward to and super excited for.

all in all, I genuinely enjoy this thriller.

Thriller • Mystery • Suspense • Crime Fiction
Expected Pub • 28 January 2025

Thank you to @minotaur_books for the e-book!

➷➷➷•·.·’’·.· A serial killer is on the loose. Plot twist: the serial killer is hunting serial killers in this cat-and-mouse chase...

But this case has been assigned to a special unit in the FBI called PAR: Patterns and Recognitions. They’re a group of puzzle solvers, brainiacs, math geeks, expert profilers, and other such brilliant misfits. Also known affectionately as the “Head Cases”.

I binged this book in a single day. Not only because it was Dec 30th and I was getting one last book in for 2024, but also because it was fast paced and legitimately one of those ‘once you start you can’t stop’ kinds of books.

I love books with nerdy awkward types; neurodivergent Gardner Camden was loveable in his quirks and faux pas. However, he is smart enough to compensate and cover most of the time, adapting himself to what is expected of normal polite society.

Not just Gardner — his entire team is pure brilliance combined with their faults and humanity. I also loved Gardner’s mother, whose wisdom is always with him in his head, and his daughter. Character development was on point and I stayed at the edge of my seat as the targets become more personally linked to the agents’ past cases.

This book is the start of a series that I hope gets a screen adaptation because I would definitely watch it! Highly recommend if you are looking for a fast paced suspenseful crime thriller with a law enforcement spin.

➶➶➶ This book releases on January 28! ➷➷➷

Head Cases” is an intense psychological thriller that keeps you on the edge of your seat. FBI Agent Gardner Camden has a brilliant mind and a unique skill set; he's incredibly good at making connections and seeing patterns in complex criminal cases. However, when Gardner is called to the scene of a crime, he realizes he has made a significant mistake. Caught in a game of cat and mouse, Gardner must think fast to uncover the identity of a copycat vigilante who threatens to expose the FBIs secrets.

The plot was masterfully woven by author, John McMahon. It must have been an enormous undertaking to write a plot as complex as this one. The investigation is filled with well-connected clues and discoveries, each one building on the last to push the story forward. I also enjoyed the character development and learning more about each agent as their stories progressed.