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.

"Head Cases" by John McMahon is an exhilarating start to the PAR (Patterns and Recognition) series, featuring FBI Agent Gardner Camden. Camden is a brilliant yet socially awkward agent, making him an unconventional but fascinating protagonist. The PAR team itself is a group of quirky, “misfit” FBI agents who rely on their analytical prowess to crack complex cases. Their latest challenge? A serial killer targeting other serial killers—a perfect puzzle for this unique team.

The novel provides a deep dive into Camden’s mind and personality. His quirky thoughts—like calculating the millimeters of someone’s Adam’s apple or counting prime numbers to calm himself—add an intriguing layer to the story. While his eccentricities might not appeal to everyone, I found them delightful and relatable, especially if you're a math enthusiast or self-proclaimed nerd (like me!).

The supporting characters shine as well, each contributing a unique skill set to the team. The killer leaves a trail of clues, challenging the team to predict the next victim and uncover whether the killer has an accomplice.

I’m eagerly anticipating the next installment in the series!

Thanks to St. Martin's Press, John McMahon, and NetGalley for providing me with the opportunity to read this ARC and share my honest review.

I have been a long time fan of Criminal Minds and one of my favourite characters on that show was Spencer Reid. So when I started reading Head Cases, I knew I would love this entire book.

Gardner Camden is genius level at solving puzzles and memorising information. He works for a special unit of the FBI called PAR (Patterns and Recognition) The team is full of a lot of screw ups, but they do things that other units cannot do, and that is find clues and put together patterns quickly in order to capture their bad guy.

The entire book is very fast paced, the clues are sprinkled throughout and the puzzle comes together so well by the end of the book. I am very excited to read more about the PAR unit in future books

Thank you to Minotaur Book (St Martin's Press) for providing me with an arc in exchange for my honest review. Head Cases will be available at your local book seller or library on January 28 2025.

4.5 stars

The Patterns and Recognition team (“PAR”) at the FBI, derogatorily referred to as the Head Cases by other FBI agents, is hunting a killer who is slowly murdering other serial killers and leaving clues and riddles for the PAR team to decipher. Their intelligent leader, Gardner Camden, is neurodivergent and often struggles to effectively interact with others. The unit is composed of outcast agents, all misfits who have been assigned there because something they worked on previously went sideways, but each is also incredibly bright. The quirky characters are well crafted, the mystery is a puzzler, and the twists and turns are so engaging. And while the focus is on finding the killer, McMahon does a wonderful job weaving in details about the characters’ personal lives and what makes them tick. This is the start to a new series, and I am already excited for book two. Head Cases is a good fit for people who like intelligent mysteries with unique protagonists.

Thanks to Minotaur Books/Netgalley for the advanced copy of this book for review.

This dad read Head Cases by John McMahon, Book 1 in his new PAR Unit series. This crime thriller revolves around a group of ragtag FBI agents known as the Patterns and Recognition (PAR) Unit. The team consists of agents who are slightly left of center and whose professional careers are hanging by a thread—just like the unit itself. Agent Gardner Camden is the de facto leader, whose personality quirks and neurodivergence make him a straight shooter who often has to course-correct. Although brilliant, he’s juggling his career, being a single parent, and now a serial killer who’s targeting other serial killers. Along with Gardner, the PAR team includes a mathematician, a weapons expert, a computer analyst, and their actual leader, a career agent. Can this team discover the killer’s identity while trying to prevent the next murder?

As a fan of crime fiction, Head Cases checked so many boxes for me. It has a breakneck plot filled with shocks and twists, a cast of characters who are immediately identifiable and relatable, and leaves you begging for more once the final page is read. This is a popcorn thriller, and I mean that as a compliment! McMahon also gets bonus points for mentioning crime fiction royalty, Michael Connelly—an author he obviously respects and is inspired by.

For as relatable as the characters are, I do feel that a few of them fell into tropes that didn’t quite feel authentic. The lead character, Gardner, is neurodivergent, which is treated more as a kooky character trait than a complex part of his identity and it could have been handled with a bit more care. McMahon makes it clear that Gardner’s quirks ultimately serve him and the team, but I wish it was more explicit that his differences are what make him strong. Additionally, one of the PAR agents is a twenty-something Gen Z-er, and her dialogue often felt slightly out of touch—more like what an older generation thinks kids these days talk like. This took me out of the story a little, but it’s a minor criticism that didn’t detract from my overall enjoyment of the book.

If you’re a crime fiction/thriller fan, you will devour Head Cases. McMahon sets up a case that kept me guessing and entertained the entire time, I give it 4/5 and highly recommend it!

A quick and engrossing read. This is a solid cat-and-mouse procedural with a strong cast of characters and a plot that provides complexity without becoming convoluted and confusing. It is complicated enough to hold interest and entertain, without requiring note-taking or a full blown evidence board. The overall vibe is a TV show (think Criminal Minds or NCIS plus Dexter) in book form – easy to consume and satisfying.

But what I liked most about this book is Special Agent Gardner Camden and his fellow investigators in the PAR [Patterns and Recognition] unit. The depiction of Camden is pitch perfect, straight-forward but done with care. He is an analytical genius with an eidetic memory who knows his brain works differently from everyone else. Told from a first-person POV, we get to see and hear that mind working through the facts of the case, the politics of the bureau, and all social situations and interactions. He synthesizes information, analyzes situations, and throws out interesting facts in a business-like, unfiltered manner that he is told is arrogant – but which I found highly entertaining. His personal life has commonality with similar characters in this genre, but there are a couple of really interesting elements adding complexity and tension to his everyday life. Altogether, Gardner Camden is a fascinating character.

The rest of the unit is not as well developed: we get the profiler, the mathematician, the sharp-shooter, and the just-graduated-top-of-his-class rookie whose addition to the team is shrouded in secrecy. This book is the first in a series, so I hope these as-yet largely undrawn characters develop more depth. They are individually, and as a whole, full of potential.

This book is great entertainment and I look forward to the next installment in the series.