A great start to a new series. Started a little slow but then took off running! Highly entertaining for anyone who loves FBI profiler mysteries or True Crime.

This book was definitely one of my favorites so far this year. I love that the characters are all misfits in one way or another and have all epically messed up somewhere along the line, but all have their own unique skills that somehow manage to mesh together to carry a book that I couldn't put down. The plot was fast paced but nothing about it seemed rushed. The characters were fun and very multidimensional. I cannot wait for there to be more to this series and am very much looking forward to continuing it in the future!

This was a good debut! If you love police procedurals that follow a serial killer, then give this one a try. It is a bit slow paced at first, and while less dark than I expected, I enjoyed the storyline. I found Camden's character well fleshed out and his methods intriguing. I do wish we had a bit more background on the other members of the PAR unit (patterns and recognition) but maybe we will get more in the sequel!

Rating: 3.5/5

Thank you to St-Martin's Press, Minotaur books and NetGalley for the ARC. All opinions are my own.

This book gives TV show vibes—think Law & Order or Criminal Minds. The book centers around PAR (Patterns and Recognition), a unit of the FBI, composed of highly skilled individuals that are a bit quirkier than typical agents who are able to think outside the box. I’m glad to hear it’s a series because we get to know each member of the team during Headcase and I can’t wait for their characters to develop more.

In Headcase, Agent Gardner Camden responds to a call regarding a murder victim believed to be a serial killer. The way he died was unconventional and there are many unique clues that make PAR perfect for the case. As PAR begins their work on this murder, another serial killer comes up murdered and the patterns continue…the only problem is, it seems like the suspect might be inside the house (figuratively).

Camden has a job to get ahead of this new serial killer before those he cares about, or even himself, may fall into the killer’s hand as their next victim.

This book was engaging and Camden’s character was well fleshed out. I loved his unique thought process that the writing detailed perfectly. The story was gripping and I seriously was trying to put all the pieces together to figure out the killer myself (spoiler, I did not).

Thank you to Minotaur Books, St. Martin’s Press and NetGalley for the ARC.

Readers who love cat and mouse thrillers, serial killer profiling, and police procedural will want to pick up Head Cases by John McMahon. I found the writing captivating and increasingly claustrophobic as the showdown between a FBI agent in the Patterns and Recognitions Unit is attempting to identify and take down a killer. A mystery with cryptic clues, taunts, and increasing danger, this was a superior thriller!

Thanks to St. Martin's Press and NetGalley for the digital ARC of this book. First of all, I am happy that it is a series because I enjoyed this first book and look forward to others. I am admittedly a big fan of FBI/serial killer profiling and also puzzles/codes etc. so this was right in my wheelhouse. The characters were engaging and the story felt well paced. I also enjoy a well fleshed out villain which this book delivered.

3.75 Stars

Head Cases is the first book in a new series, and it certainly began with an interesting scenario. I found the intricacy of the case intriguing and as a result, was glued to the pages and was quite fascinated by the team's investigation. Because this is the first book in a new series, there is a certain amount of time taken to introduce the characters and develop their unique personalities, something I appreciated. But while the case was definitely interesting, it did fall back and make use of some tropes I was hoping would be avoided.

I really enjoyed the main character quite a bit. Gardner Camden is on the spectrum and I appreciated the author's research into this character's development; he was such a fascinating person to follow. Quite brilliant, but struggling with personal relationships, it was fascinating to see how his mind grasped concepts with which the rest of his team struggled, but completely missed nuances relating to social relationships. The rest of the characters complemented each other very well and I really enjoyed learning about their unique quirks and talents. While this book focused more on Camden's relationships, I am guessing future books will reveal more about the other characters and I can't wait as the glimpses we got were fascinating. All of them are there for something they did in the past and the author gave us just enough to tantalize.

The plot certainly began and ended with quite a bang, but the middle did slow down quite a bit. I didn't mind too much as I really enjoy investigations and love learning about the political machinations of organizations the author wants to include in their books. The themes of family, loyalty, secrets, and betrayal all found their place within the story line. I also didn't mind that the focus was more on Gardner Camden than on the others as I feel the author will expand on the characters in future books. However, I did wish the overall conclusion was a bit different than what it was as it was predictable and a bit tropey. I also didn't feel like the author took it as far 'into the dark side' as the subject merited. It felt like the author was afraid to go too dark and the brevity sometimes felt off as a result.

Head Cases was an intriguing first entry into a new series and I enjoyed the character development quite a bit. And while the plot was interesting and definitely had its high moments, especially the first thirty percent and the last twenty percent, overall I did find it somewhat predictable when the final outcome was revealed. I was really hoping it would have gone in a different direction. However, I did enjoy it and I will be looking out the second book when it is released.

I couldn't stop reading this! It was fantastic and intriguing!
I hope that this is going to be a long series!

I absolutely loved this read from start to finish! The plotting and pacing is absolutely on point, but what REALLY stood out to me is the character of Camden. There’s a Jason Bourne element here – a person who takes in too much analytical data at any given time without the ability to shut it off. Camden struggles to connect with people - and perhaps, at times – even his own feelings, but I appreciated how much I was able to feel for the character and the situations he was in despite a held-back character and writing style. It seemed like heightened drama was conveyed with very few words, and there was something about this tight, held-in nature that made those moments even more moving and impactful.

He is a perfectly imperfect hero, and I really felt like I was in his brilliant yet flawed head.
I kind of fell in love with Camden and his impetus to do the right thing no matter the cost, and I was so glad to learn that there’s another story with this character on the way!

This book – and hopefully series – is in the vein of the series Slow Horses (based on the Slough House series by Mick Herron), which is described as ‘an administrative purgatory for MI5 service rejects who have seriously failed a task but not badly enough to get sacked.’ Have I read or watched much of these? No – I’m not really into police procedurals, as I said, but my hubby has been RAVING about Slow Horses, so I’ll likely give it a full watch soon.

There’s something about rooting for the underdogs when they’re trying to save lives by bringing down bad actors while also trying to navigate within a bureau that is hostile to them. Talk about heightened stakes and DRAMA.

I highly recommend this read and can’t wait fo the next book!

Thank you St. Martin’s Press for the ARC!

"Head Cases" is a gripping, fast-paced police procedural that hooked me right from the start. As a huge fan of Criminal Minds, I was very excited to read this book about FBI agents in the Pattern and Recognition (PAR) unit, and it did not disappoint. It was such a page-turner, and I had so much fun reading this book. The mystery was compelling, and I was fully invested. I loved the well-developed, quirky characters, and the plot twists were surprising and well-executed. I was ecstatic to learn that this will be a series, and I can't wait for Book 2!

Thank you to NetGalley and Minotaur Books for the ARC in exchange for an honest review.

Overall this is a compelling story with really great characters and plot. The story has a good pace to it. Quite a few twists and turns I didn’t expect.

Thank you NetGalley for the copy

head cases by John McMahon published by St Martin press is a must read for all fans of Criminal Minds and profiling. The book follows a group of FBI agents as they hunt down a murderer.

Camden Gardner is great at solving problems and works at the FBI. He is an analytic genius with a love of puzzles.
Cassie Pardo is his police partner and they are part of the PAR unit. Par stands for Patters and Recognition unit.

The PAR unit is made up of a mathematician, a weapons expert, and a computer analyst. The FBI brings them in for cases no one else can seem to solve. The DNA on a murder victim comes back to a serial killer they thought died long ago.

The PAR unit usually works on cold cases but this is an active case and since none of them specialize in people, can they protect themselves and their loved ones before it's too late?

Huge thank you to John McMahon for partnering with NetGalley. I received an advanced reader copy of this book in exchange for my honest opinion and review.

This was a quick and easy read! A loved all the action and puzzles. I hope to read more from this author in the future!

Thank you NetGalley and Minotaur Books for this ARC in exchange for an honest review!

Gardner Camden, an FBI agent on the PAR (Patterns and Recognition) team, is part of a group of skilled but reprimanded agents. Despite their past wrongdoings, they’re known for solving cases that stump others.

The team is called in when a serial killer, supposedly killed in a fire years ago by Camden, is found dead. Soon, another serial killer turns up dead, and the team realizes this murderer knows more about the FBI than any civilian should.

How will the team protect each other and their families? Who is the next target?

Binge alert! I need more. My mind was constantly racing with possible scenarios. The PAR team’s flaws and strengths jump off the page in such a brilliant way.

There are no stereotypical heroes here—these are underdogs I wanted to root for and understand, with excellent character development. The descriptions were top-notch, making you feel like you’re running alongside the team.

The plot unfolded brilliantly, with perfect pacing. I can easily see this being adapted for the screen. I’m already looking forward to what’s next for the PAR team—just what I need, another series to add to my TBR!

Thank you NetGalley and Minotaur Books for this ARC!

I really tried to make it through this book, but it was just simply too gruesome for me. The characters did seem interesting, but I couldn't get past the graphic nature, which I'm sure was likely required in some way, but I couldn't stomach it. What I did read of the novel, it seemed well paced and the characters unique and interesting.

John McMahon’s "Head Cases" launches an electrifying series that pits an enigmatic FBI unit against a serial killer with a chilling agenda.

The Patterns and Recognitions Unit—led by the sharp but socially inept Special Agent Gardner Camden and rounded out by math-savvy Cassie Pardo and rookie Richie Brancato—is tasked with solving a macabre puzzle. The discovery of Ross Tignon’s mutilated corpse, marked with the chilling resurgence of a man presumed dead, is only the beginning. When another infamous killer, Barry Fisher, meets a gruesome end shortly after his parole, it becomes clear that the FBI is up against a predator targeting serial killers in a twisted crusade of vigilante justice.

The plot masterfully ratchets up tension with every turn, from cryptic clues and taunting phone calls to the antagonist’s unsettling omniscience within FBI systems. McMahon crafts a deadly game of cat and mouse between Camden—whose razor-sharp analytical skills are matched by his haunted past—and the killer dubbed "Mad Dog." The antagonist’s warped sense of righteousness and cunning make for a chillingly effective foe. Camden’s interactions with his team, especially the contrast between his cerebral methods and his teammates’ more humanistic approaches, add depth to the procedural narrative.

Packed with intrigue, "Head Cases" is a superior thriller that balances razor-edge suspense with dynamic character development. Camden’s intense focus and the emotional stakes tied to Mad Dog’s threats to his loved ones keep the story both cerebral and deeply personal. McMahon’s pacing is relentless, ensuring readers are glued to the page as the revelations unfold. This gripping start to a new series is as chilling as it is satisfying—a must-read for fans of psychological cat-and-mouse thrillers.

This book was a pleasant surprise.
I thoroughly enjoyed it, as it was a quick read and a good time.

What can I say about John McMahon’s Head Cases that hasn’t already been said? I read it in one sitting. This is March and I already know this book is going to be in my Top Ten Books of 2025, probably in my Top Three. I’m going to need more than just the two books under contract in the PAR Unit series. Criminal Minds. Fresh approach to crime fiction. Endearingly quirky characters. Etc., etc.

I rate this 4.75 stars and recommend it to just about everyone. Read the book, y'all; you won't regret it.

Thank you to NetGalley, Minotaur Books, and John McMahon for an advance copy of Head Cases in exchange for an honest review.

Alright my crime fans, did you love Criminal Minds as much as me?? Let me introduce you to your new obsession- THE PAR UNIT!!!

Everything about this book hooked me from the first sentence and didn’t let me go until the end. I want nothing more than another PAR case asap.

If you don’t pick this up now, you’re truly missing out!!!

I personally adore police procedure books that follow a similar path as Criminal Minds, and Law and Order. So when I got accepted for this book I was beyond excited to read my first book by John McMahon.

McMahon uses a neurodivergent character, who is amazing with puzzles, but finds people to be the hardest puzzles. This leads to an interesting dynamic amongst the main characters and those he interacts with such as his daughter. I adored the puzzle aspect and the suspense of what the killer wants from Gardner and his team.

The action in this book was so good and I adored the whole process throughout the novel. If you like thrillers/mysteries with a lot of puzzles and action it would be a great book for someone to pick up.

Thank you for the eARC in exchange for an honest review.