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.

[Thank you to the author, publisher and NetGalley for allowing me to review this ARC with honesty.]

I am a person that likes crime shows but what I really like are the Criminal Mind/Mind Hunter types that try to get inside the psychology of the crimes in order to track said criminal down. This is a novel in regards to those who look for patterns and analyzes cases with data that he's collected into his mind. Agent Camden gives a sort of Spencer Reed vibe [from Criminal Minds] but add [The Good Doctor] outlook.

This is the first in a series I believe and it was a very intriguing ride through Gardner Camden's life as well as those around him. You follow along as a case unfolds that ties back to past ones and trying to find the connection.

I had a lot of fun watching the different relationships he had with the other characters including his partner, his boss playing second fiddle and a gun toting Annie Oakley persona and a very new incomer to the team that has his own secrets.

Lots of lead up, at times a little slow paced but it gave you time learn each case.

Will be reading the continuation.

My Rating: 4 Stars

Thank you Netgalley and St. Martin's Press/Minotaur Books for the ARC.

"Head Cases follows an enigmatic group of FBI agents as they hunt down a murderer seeking his own justice..."

I'm always somewhat trepidatious about reading police procedurals as undoubtedly, there is always some aspect of the story that I find unrealistic/inaccurate.

However, I only found a couple things in this book, and it was nothing that caused me to want to stop reading.

Just in case you're curious, suspects (1) on trial for multiple murders, or (2) serving a lengthy prison sentence are not held in a safe house for their own protection. The prison system doesn't care about people that much.

This is the first book in a series. I liked the quirky characters in PAR, an FBI group assigned to track down a serial killer taking out other serial killers.

It took me a bit to get into the flow of this one, as the writing style confused me. I wasn't sure who the voice was for certain chapters, but once things started to pick up, this resolved itself.

The mystery element kept me engaged and I thought the pacing was pretty good. Some of the writing seemed a little clunky, but it was still an entertaining read.

The second book is scheduled to come out early 2026. I would read it, if only to see what this group of misfits got up to next.

⭐⭐⭐⭐

Available 1.28.25.

Agent Gardner Camden belongs to a department of misfits in the FBI. Each banished to the Patterns and Recognition unit for a variety of mistakes, they’re usually the final ask when a department hits a wall. Now faced with what appears to be a killer murdering serial killers (and at a rapid rate), Agent Camden and PAR are faced with their biggest challenge yet.

This book had a Dexter type feel and I truly thought I had it figured out in the beginning but I had no clue. Full of twists and spins and a merry band of quirky characters this new release is sure to keep you guessing!

An enjoyable detective mystery. Loved the MC, Gardner.
I received a complimentary copy of this book. Opinions expressed in this review are completely my own.

First in a series. Good characters and solid story. Looking forward to next book. Thanks to Netgalley for the opportunity to read this book

This was like reading an episode of criminal minds. I just love a good crime drama. I thought the plot was solid. I liked the idea of highly intelligent, slightly quirky, FBI agents hunting a serial killer of serial killers. I’m not sure I would say I was on the edge of my seat but I was highly engaged in where this story was going for the entire book. The storyline had complexity without being confusing. There was one little twist with one of the characters but for the most part there were no “shock and awe" tactics that made the story feel unrealistic. I felt like the author stayed true to “real-life” experiences. The characters had charm, intelligence and meshed really well together. I liked being inside the mind of Gardener Camden. He was such a complex character. I love the relationship that he had with his mother and his daughter. He was tough at times and vulnerable at other times. This is the first book in a new series and I am already looking forward to the next one. I would definitely recommend this one to any reader that enjoys a good crime drama.

Ever since I read about Head Cases last year it has been on my 2025 watch list. I was so excited to get the opportunity to read an advanced copy of the book. John McMahon has created an FBI procedural novel about a unit called PAR, patterns and recognition. I really enjoyed getting to know the agents that make up the team. Especially the team leader, Gardner Camden. The cat and mouse of the case they are on has the team going to multiple states to identify the serial killer. I really enjoyed the layers and mystery of the case and how it all unravels. This is an excellent start to what I hope is a long series. I really look forward to reading more about this team and the cases they will face. Mark your calendars for January 28th to pick yourself up a copy of Head Cases by John Mc Mahon. Thank you to St. Martin’s Press - Minotaur Books and NetGalley for the ARC.

I wanted to like this book more than I did - I felt it was a bit slow paced for me to stay fully interested. Because of the pacing, it took me much longer to read this than it should have. Overall I liked the direction of the story, like a Criminal Minds episode, but the pacing issues were hard to get over.

Book review 📖

📜Head Cases
✍️John McMahon
📠St. Martin’s Press/Minotaur Books
📚Mystery/Thriller Fiction
🗓️Pub date: January 28, 2025

⭐️⭐️⭐️⭐️⭐️

✨Thank you @NetGalley and @minotaur_books for providing me with an Advanced Reader Copy of this book in exchange for an honest review. Also thank you to @johnmcmahonbooks for writing a masterpiece—I was riveted from the very first page!

✨When a DNA hit comes back on a dead body to a serial killer long presumed dead, a special unit of the FBI is called in to action. The (PAR) Patterns And Recognition Unit is called in for unique circumstances and cases that are practically unsolveable.

✨ Heading the investigation, FBI Agent Gardner Camden, an anylitical genius, has to retrace patterns and steps of a violent killer, who seems to be targeting serial killers.

✨ Alongside his team, which also consists of a mathematician, a weapons expert, and a computer analyst, Gardner has to solve the riddle of the killer’s identity before the encroaching perpertrator can turn on them.

✨I loved every minute of this. A cross between Karin Slaughter’s Will Trent series and Mindhunter, I enjoyed the quirkiness of the agents and our main character and his position in the FBI. This is a gritty, puzzling, WILD, and gruesome cat-and-mouse game and I couldn’t get enough.
I don’t know where John McMahon’s books have been hiding from me, but I’ll be going back to read everything he ever wrote. This one will be a big hit—read this now!!

#netgalley #headcases #johnmcmahon #stmartinspress #minotaurbooks #advancedreadercopy #arc #bookreview #bookstagrammer #winterreleases #thrillerfiction #readthisnow

The Patterns and Recognitions (PAR) unit of the FBI is made up of misfits, agents who all made some mistake in their previous assignments but have unique skills. I love the idea of this type of an investigative unit. They remind me of some of my favorite TV detectives, Monk and Will Trent, to name a few. They see things that others miss. While the crimes were a bit graphic, they were cleverly investigated in a way that made me happy to be in the minds of these agents. If you like police procedurals with unique characters, this one is for you!

4.5 stars

Enjoyable read, Really liked it.

Will be waiting for the next one in the series.

Well done.

Gardner Camden is neurodiverse, something his beloved mother has taught him to see as a gift and to manage in the real world as he was growing up. In fact, his brilliant analytical mind and talent for solving puzzles has made him one of the FBI’s most interesting agents. What he lacks in interpersonal skills, he makes up for in methodically solving cases other agents can’t.

His team, the Patterns and Recognition Unit (PAR), includes a group of quirky but skilled personnel who are loyal to a fault: a career agent, a weapons expert, a math whiz, and a computer analyst. Aside from his young daughter, this is his family.

Camden is made lead on a case he worked years prior when DNA connects a murder victim to a serial killer who was supposed to have died years before. His death mimics that of his victims, the killer leaving clues that set the team in motion.

And then, there’s another victim. Another clue. Another victim. Another clue.

When it becomes clear the clues are meant specifically for Camden, the team - normally relegated to desk work - hits the road to travel the south from Alabama to Texas to Arizona as the killer sets a trap.

The serial killer is killing serial killers, but what does it mean and where will it end?

This procedural works because of its fantastic characterization, the unique voice of Camden, and exploration of the motivations of the killer and the agents. It’s psychological aspect, as much as the descriptions of the gore, that push this to the top of the class.

As the first book in the series, McMahon has set something special in motion. Laying out an unexpected backstory for Camden and creating an enigmatic supporting cast capable of being the focus of any subsequent book in the series feels exciting.

This is a series I eagerly anticipate reading as each novel is released. It’s fantastic, filled with tension, action, mind games, and red herrings.

Don’t miss out!

I was thrilled to be approved for this. I immediately dove in, and couldn't put it down. While the beginning was somewhat slow, it didn't take me long to become engrossed with the characters and story. I love the writing style of this author. I am so excited this is a series. I cannot wait for the next book in the series.

While the success of a team of misfit detectives who manage to get the job done in their own ways may not be a new plot line, The characters in HEAD CASES are originals and are very good at their job, well, they are good at this job. Each member of the team has been placed in the PAR Unit after their particular skills landed them in hot water elsewhere. They are originally assigned to apply their pattern recognition skills to cold case reviews. BUT, when a serial killer's body is found, it raises alot of questions to which this team must find the answers.

This is slated as the first book in a new series built around the PAR team. John McMahon has had success in police procedural series, he's the author of the PT Marsh series, an excellent series itself, but has given the cast of the PAR Unit a human touch. Their differences were divisive in the prior jobs, here, their differences make them unique members of a unit ready to prove their abilities as they wreck havoc on the FBI. The personal background of each will be excellent stories in the coming series. 5 stars for Head Cases. Can mcMahon do it again?

I read and listened to an audio book of this story. Each was equally good with the audio adding an extra element to the book. Readers will be happy with either version.