3.5 stars.

This was pretty middle of the road for me. It is 100% police procedural so don't expect any sort of character depth or other point of view. I enjoy some aspects of detective books but they usually have other elements that I like in them as well, including points of view from the killer they are chasing, or deeper looks into their personal lives. This is fast paced, with some moments of unbelievability. The PAR unit that Gardner our main character is in is known to be a super intelligent group. Some conclusions they make appear to come from no where but strictly vibes. The most in depth or meaningful quotes from this book come from Gardner's mom, who has nuggets of wisdom sprinkled through that I enjoyed. I wish we would have had more scenes with his mom or his daughter, or more meaningful interactions with his partners. I understand that isn't the type of book the author wanted to write and that's fine. Just not my ideal type of story. I would recommend this book to fans of fast paced police procedural TV shows.

Head Cases, written by John McMahon, follows a mysterious group of FBI agents on a thrilling pursuit of a murderer who is seeking his own form of justice. This electrifying debut in the series promises to captivate readers with its commercial appeal and gripping storyline.

4.5 stars! Rounded up to 5! This was such a fun smart book! I really hope there’s another book going to be coming!

🕵️ Head Cases by John McMahon OUT JANUARY 28th!! 🕵️

This is the first book I read in the new year! If you love the tv show Criminal Minds like I do, then Head Cases is for you!

FBI Agent Gardener Camdon is a genius and is most useful on the fbi using his analytic brain to solve cases. He is part of a group that is like the misfits, a quirky group of people with a past at the FBI. But what happens when a killer starts killing other serial killers and leaving clues in order to taunt them.

I really liked this one! The main character really reminded me of Spencer Reid from Criminal Minds. I love the mystery and seeing how his brain worked to solve the cases. There were a lot of characters and sometimes it was hard to follow, but I think most people will enjoy this read! 4✨

This is one of those books that I had the opportunity to read thanks to the fine folks at NetGalley. I went to the NetGalley website last evening in an attempt to read another book (for which I had previously been approved) but was unable to because it had already been archived. So I decided to look at other books and publishers and that is how I arrived at this selection. And with that, I would like to prevent my review of Head Cases by sophomore author John McMahon. This book is scheduled to be published on 28 January 2025.

When I started reading this novel, I entered with some trepidation as I had never heard of this author and I was unsure of what the novel was going to be about. I can honestly say that after reading this introduction to a new series that I will be eagerly awaiting the next books in this future series.

The protagonist, Gardner Camden, is a walking analytical brain with an affinity for riddles, puzzles, and codes. It makes him the perfect fit for the Patterns and Recognition (PAR) unit of the FBI, a team of five brilliant but misfit agents tasked with solving cold cases. Gardner's smart, but he's all business--except for his seven-year-old daughter and occasional visits to his elderly mother, he prioritizes his work and justice over everything else, no matter the cost. With rumors of PAR about to be disbanded, the team can’t afford to make any mistakes.

A serial killer from one of Gardner’s solved cases, presumed to be dead for almost a decade (seven years, actually), is found murdered, and then soon after, another body with a similar story. The mastermind murderer has left clues and riddles for Gardner and his team--a mathematician, a sniper and weapons expert, a computer analytics specialist, and their leader, a career agent--as they track him across the country. With the threat of PAR dissolving, Gardner must work to solve the riddles before it’s too late.

McMahon’s suspenseful and irresistible thriller confronts the scales of justice in the face of a twisted vengeance plot as this engaging cast of characters works together to stop a misguided vigilante.

After having finished this novel in two days, I think that I would have to agree with the opinion of the New York Times Book Review, who had previously called McMahon “one of those rare writers who seems to have sprung out of nowhere” and whose (debut) novel is “pretty much perfect.” As such, I would have to say that this book is worthy of a five star rating. I believe that this novel would be a definite fit for aficionados of the FBI/Crime genre and believe that readers of Patricia Cornwell, Thomas Harris and Jeffrey Deaver.

As with all my literary ramblings, this is just my five cents worth.
Edit Review

I have long been a fan of author John McMahon’s work. See his three-book series that starts with The Good Detective. So, when Head Cases came up on NetGalley, I quickly put in for it. Even though I had quite a few already assigned to me, Minotaur Books quickly approved my request. Very glad they did that. Especially since the book is so very good.

FBI Agent Gardner Camden has skills. Not social skills as he has a hard time reading people and situations and, as a result, he is awkward. After a recent event, he does not venture out of the field office in Jacksonville, Florida. He prefers it that way as his skills are aimed at solving riddles and enigmas, and has an incredible wealth of knowledge. His ability to solve things is why he and his partner, Agent Cassie Pardo were put on a plane and sent to DFW airport.

How does a dead man die twice, years apart?

Ross Tignon, identified as being dead years ago, is very much dead again. This time he is dead on his kitchen floor, next to the kitchen island that borders the living room. The blood pool under the body trails over to and under the refrigerator.

Back in 2013, Ross Tignon was the suspect in a series of murders in Florida. Agent Camden was on the hunt, chasing him down while he built the case, and then a fire occurred in Tignon’s home. While his wife was brought out, injured but alive, a male was not so lucky. Dental records indicated that the body was Ross Tignon. At, least what was left of him one the fire was out.

The man on the floor, known to the locals as Bob Breckinridge, is Ross Tignon. Clearly, he did not die easy as he was cut open wide in the stomach area. He was cut again in his chest. The killer cut the numbers “5” and “0” into his chest. Agent Camden has no idea what the number could mean though, Agent Pardo thinks it might represent the police, aka 5-0.

Agent Camden, Cassie, and three other folks work in a specialized unit of the F.B.I. known as PAR for Patterns and Recognition. Their job is to consider cases that are stalled. Review them, identify peculiarities in them, and offer new theories of investigation. PAR then gives the case back to the relevant field office or sends it to headquarters. They don’t go into the field because everyone in the unit has a particular quirky skill that is useful and a history of screwing up in some way.

Being sent out in the field never happens. Yet it has this time. The reason was that it was supposed to be because the boss wanted Agent Camden to see the body and verify it really was Ross Tignon. With that being done, they should be soon on their way back to the home base in Florida.

Instead, and just after they turn the scene over to agents out of Dallas office, they are sent to Rawlings, New Mexico. After serving thirty-one years for multiple murders back in the 90s, Barry Fisher was just released days earlier. Every agent studies his case in the FBI Academy. He is a legend in bad way. He is now dead and Camden and Pardo are headed to New Mexico.

Not only that, but in a first, Agent Camden will lead the investigation. A serial killer is killing serial killers.

What follows is a fast moving and complex police procedural. While the focus is on Camden, the rest of the team and several other characters are fully developed and multifaceted. So too is the killer who the reader gets to know through the working of the case. Not by the usual mind of the killer POV technique in dedicated chapters that so many authors use. The absence of that predictable and utterly boring author technique was a major relief to this reader.

We learn everything from Agent Camden’s perspective. A man that has special skills, a different way of looking at the world, and a very hard time fitting in with people. A character that very much spoke to this reader.

According to the author’s acknowledgment at the end of the read, this is the first book of a two-book contract. The second in the series will come out early in 2026. I was thrilled to read this news. Head Cases was/is a great read and very much worth your time.



My digital ARC reading copy came from Minotaur Books, through NetGalley, with no expectation of a review.


Kevin R. Tipple ©2025

Wow! This was such a clever and entertaining read, a perfectly written crime novel that kept me guessing. I loved the character development of main character Gardner, who was written in such a way that I felt like I was in his headspace.

One other thing that I appreciated was the minimal use of profanity. Strong language so often plagues books in this genre, and it made for a refreshing change to not have that distraction.

I will definitely be reading the second book in this series!

I am excited to share I recently discovered a new, exciting author and thriller by John McMahon that will keep readers on the edge of their seats.

A gripping new thriller by John McMahon that promises to keep readers on the edge of their seats! This intense narrative delves into the chilling world of serial killers through the lens of a uniquely formidable group within the FBI. When a wave of serial killers turns up dead, the elite Patterns and Recognition (PAR) Team springs into action. Led by the brilliant Gardner Camden, they race against time to track down a new killer while being taunted by a mysterious vigilante.

Determined to halt the escalating violence and bring their prime suspect to justice, Camden and his team must stay one step ahead in a complex game of cat and mouse.

McMahon crafts an action-packed tale that grabs your attention from the first page. Those acquainted with Gardner Camden's thinking know he's a master at piecing together puzzles, often spotting details that elude everyone else. Some might see his talent as a hint of autism or savant-like abilities, but his unique perspective is invaluable in the high-stakes world of the FBI.

Typically called in when other teams falter, the PAR Team excels at solving cold cases. But this time, they're thrust into a fiery scenario where discretion is paramount. Camden— is faced with the challenges of untangling a web of deception while confronting the shocking resurgence of a supposedly dead serial killer. The dynamics of Camden's personal life add another layer of complexity to the narrative. His struggles to maintain a relationship with his estranged wife and daughter, who struggle to understand his quirks, and the dedication he places on his job further humanize him while serving to illustrate the psychological toll of his profession and the societal disconnect he faces due to his analytical disposition.

As bodies of serial killers pile up, the team grows increasingly uneasy about the possibility of a vigilante on the loose—someone bent on cleaning up the remnants of the FBI's past failures. The stakes couldn't be higher, with rumours swirling about the PAR Team's imminent disbandment. When the elusive killer begins to toy with Camden, leaving behind cryptic clues, the countdown begins to unveil a foe determined to make their mark and ensure these brutal killings don’t go ignored. Gardner Camden may finally have met his match unless he can uncover the missing link.

John McMahon delivers an electrifying thriller that keeps you guessing at every turn. The narrative unfolds rapidly, weaving together a complex tapestry of clues that propel the story forward with relentless momentum. As the tension builds, readers find themselves piecing together the mysteries, only to be met with unexpected twists that heighten the intrigue. Key characters are richly developed throughout, each offering tantalizing glimpses into their pasts, leaving ample room for future exploration.

With constant revelations and surprises, the plot maintains a sense of ongoing mystery that gradually unravels hidden truths. I eagerly await John McMahon’s next installment featuring Gardner Camden, whose enigmatic character has much more to reveal.

This book is a must-read if you love well-paced, non-stop action, solving puzzles, and unravelling mysteries with compelling, realistic, richly developed characters, and you enjoy crime procedurals— prepare yourself for a rollercoaster ride of unexpected twists and turns that will keep you guessing at every turn. For those with a flair for tracking serial killers, this exhilarating read will surely grip your attention and keep you captivated until the very last page!

I had a wonderfully immersive reading experience as I alternated between the audiobook and my Kindle. Will Damron's narration truly stood out; it was fantastic. He brought the character of Camden to life in a way that felt incredibly authentic and relatable. It was as if he had stepped right into Camden's shoes, allowing every moment of the story to resonate deeply with me. I would also like to express my gratitude to St. Martin's Press/Minotaur Books and Macmillan Audio for providing a copy of the e-arc and a copy of the ALC through NetGalley in exchange for honest feedback. All opinions expressed are my own.
The expected release date is January 28, 2025

"Head Cases" by John McMahon was a gritty and intense crime thriller. The story plunges you into a dark and dangerous world, and the suspense rarely lets up. The characters are complex and flawed, adding to the realism of the narrative. McMahon's writing style is sharp and direct, creating a sense of urgency that propels the story forward. It's a gripping read for fans of hard-boiled crime fiction.

What stood out: The dark atmosphere and the relentless pacing. The complex characters added depth to the story.

What could have been stronger: Some of the plot developments felt a bit predictable.

Rating: 3.5/5 stars

I am always weary when a new thriller releases claiming to be engrossing and different; I’ve read so many that being surprised is a rarity. I was so pleased that Head Cases lives up to the hype.
John McMahon has created a memorable cast of characters, hero and villain and somewhere in between. Those who enjoy FBI investigative narratives will appreciate the time spent on procedural details. A wonderful new series to join the subgenre.

Head Cases by John McMahon is the perfect crime thriller. I mean perfect.
This book reminded me of my favorite crime series, Criminal Minds.

I love stories about the FBI, serial killers and those dynamics.

The book is so well written. I just can't even describe how fast I read this book!

This was my first book by John McMahon and definitely won't be my last.

“Head Cases” by John McMahon is about a unit within the FBI called PAR (pattern and recognition). On this case, they are searching for a serial killer who is out to killing other serial killers in a gruesome manner. DNA has shown that the killer who was presumed dead a long time ago, is alive and leaving a trail of riddles and signs that will lead the PAR Unit to him.

Liking the characters was so easy for me and I was fully invested in their success and downfalls. This is a police procedural, special unit story and a thriller/mystery all rolled into one. It is fascinating in its construction, the weaving of the characters, the perfect red herrings to the end and entertaining the whole time. I definitely recommend Head Case. I can’t wait to read the second book in the series in early 2026.

Thank you to NetGalley, the author, John Mc Mahon, and the publisher St. Martin’s Press/ Minotaur Books for the opportunity to read and review an advanced reader's copy of Head Case.

WOW. Now this is the police procedure thriller I have been looking for all my life and finally, here it is! I am notoriously picky when it comes to thrillers, and I dislike anything that seems too convenient, the plot twists aren't believable, or the author is throwing red herrings left and right to throw us off the track of the actual conclusions to the mystery.
This book succeeds in avoiding every one of these frustrating thriller tropes, and instead gives us a truly incredible mystery following a neurodivergent FBI Agent and his team who are tracking a serial killer killing serial killers. At first, I was thrown off a bit by the writing style, until I realized it's exactly how agent Camden is observing things, and then I absolutely loved being in his head. I thought it was going to be a waste of time hearing about everyone's appearance, no matter how minor the character, but it actually led to the absence of (see above) those red herrings where an author will only tell you about the way someone looks if you're supposed to pay attention to it- even if it's just to throw you off. Here, we saw everyone the way Agent Camden saw them, and were able to draw our own conclusions without any author bias in our way.
While this book was completely addicting, and stressful, and had me absolutely GLUED to my Kindle, there is also a found family aspect that was unexpected and completely wonderful. Agent Camden's team was exactly what I always wanted from a group of detectives, There wasn't that one detective who didn't want to do any of the tasks he/she was assigned, nobody was dropping the ball and causing issues for everyone else- they all worked together and respected their lead investigator- and in turn, they became a solid and just perfect team. I cannot wait for their next case and to see what they've been up to since this book's ending.
I highly recommend this book to everyone!!

The perfect read for fans of Criminal Minds and Bones, this one had me on the edge of my seat wanting more. I absolutely loved this one and enjoyed seeing the main character's growth and development. I can't wait for more to come in the series!

Rating - 4/5 stars ⭐⭐⭐⭐
Date Read - October 14, 2024
Publication Date - January 28, 2025

*I received an E-ARC of this book for free in exchange for an honest review* - Thank you @johnmcmahonbooks, @stmartinspress, @minotaur_books and @netgalley!

McMahon got me hooked from the beginning and I sped through the book, it is very bingeable and fast paced. I was expecting more uniqueness from all the PAR team members but I enjoyed getting a look inside the mmc's brain. This book is fun because we get to learn about and investigate several different mu*ders, instead of only focusing on one. I thought that kept things interesting and always had my mind working. Speaking of my mind working, I am definitely going to remember the story that Nabokov shared about coincidences!

If you are interested in mystery/thriller books with FBI agents and serial k*llers who target other serial k*llers, you should try Head Cases!

Get excited to read Head Cases, available January 28! 🎉

*Please check trigger warnings*

Loved everything about this! The mystery, the characters, the execution of it all, the TWISTS! It was all layered so intricately.

This book was very interesting to me! As someone who loved old school Criminal Minds and has read several John Douglas (creator of behavioral profiling), this book was a win! I love following along with the developments in the case and characters. I didn't realize this book was the first in a series, so I'm excited to continue with this author!

Thank you NetGalley for this ARC!

Are you an avid Criminal Minds watcher?

Is Spencer Reid your favorite?

This one is for you.

I absolutely devoured this in less than a day and I can’t wait for this series to unfold. The perfect amount of thrill, mystery, and intrigue. I enjoyed each member of this team and I’m excited to see where it goes.

Camden Gardner is a fascinating character in the way he thinks and solves twisty cases. He and the other members of the PAR Unit may be outcasts but they sure get the job done one way or another. As this is a first book and intro into this special group, it does a great job in introducing the important characters, fleshing them out as they are thrown into this case of a serial killer offing other serial killers (including one that everyone thought had died in a fire).

I like that the members of the group (Cassie, Frank, Shooter and newbie Rich) are very distinct with their own strengths and weakness (no cookie cutter characters here!). It made for a very exciting read as Camden and the others race to solve the case before more people die. Nicely twisty and thrilling! This is the first book I have read by this author but you can be sure I will try his other ones, as well as wait eagerly for more books with Camden and the PAR Unit!

Thank you to NetGalley and the publisher for the chance to read and review this book!

5/5 stars

Thank you Minotaur Books for the advanced reading copy!

I loved this book from the start! Total true crime vibes, and it almost read like a documentary. Following our MC -- quirky, lovable and brilliant Gardner Camden -- was extremely fascinating. This book kind of reminded me of UNMASKED by Paul Holes or BRIGHT YOUNG WOMEN by Jessica Knoll -- so if you liked either of these, you'll love this one. I found HEAD CASES to be even more interesting than either of those others -- both of which I loved -- and thought it wrapped up really nicely. Any serial killer story is going to be naturally interesting, but this one took a number of unique twists and turns that kept me so hooked from the beginning. Great way to end 2024's reading list!