All I can say is what a thrill ride this book was! Truly one of the best books I have read in a long time. From the start I wanted to know what happened and why it was happening. I thought it was well written and brought in some criminal minds type stuff which immediately caught my attention. The way I would describe this would be an episode of Criminal Minds with Spencer Reid as the main character!

HEAD CASES was an engaging and twisty thriller with an intriguing main character.

Gardner Camden is an FBI Agent with the PAR (Patterns and Recognition) unit of the FBI. He seems to be somewhere on the Autism Spectrum but had honed his abilities to make himself invaluable to the FBI when tough, "unsolvable" cases come in.

This story begins when a body is discovered - the body of a serial killer. The only problem is that this killer was supposed to have died in a fire years earlier. Gardner was on the original case. Then a second serial killer - this one recently released from prison - is found. Then a third murder victim - a self-confessed serial killer who was on trial - is found.

Gardner and the rest of his quirky colleagues are on the trail of a serial killer who kills serial killers and who seems to know what the team is doing and manages to stay one step ahead.

Throw in some inter-FBI politics and Gardner's relationship with his mother who is in a nursing home with memory issues and his seven-year-old daughter who is living with her grandmother, and you have a man leading a complex life.

This was excellent. I look forward to the second book in the series coming in 2026. I also want to find the author's earlier books.

A fast-paced thriller! I love Criminal Minds and the Behavioral Analysis Unit at the FBI, so the PAR unit and Camden was right up my alley! The plot was engaging, with a serial killer killing other serial killers. There were multiple red herrings, and I kept second-guessing who the suspect may be. I enjoyed the puzzles and references to mythology, as well as the things that Camden notices. I also liked the other members of the PAR unit. I will definitely read the second in this series!

Phew what a fab police procedural!!

I was so fascinated with the ongoing investigation. Such great details, characters, clues, and a mystery that keeps you turning those pages!

I was surprised how the team was able to solve the mystery despite the serial killer being one step ahead! It’s fast paced and gripping.

I’m happy that this is the first in a series and look forward to what the author has next!!

4/5

Thanks to the publisher!!

I really enjoyed this! It felt like watching an episode of criminal minds with all of the quirky details!

The pacing of the story was perfect and you really never knew what was coming next so it had a lot of twists and turns for me. I enjoyed Nolan’s character and the backstory to why he was doing what he was. This book was written very well and kept me interested constantly.

Head Cases by John McMahon
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Special FBI agent Gardner Camden is an analytical genius who excels at puzzles, but not so much at people skills. He is part of a unit called PAR (Patterns and Recognition) that is feeling unsure of it’s future as a unit. When DNA links a murder victim with a serial killer long presumed dead, PAR is sent.
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What I liked:
-The cat and mouse vibes in this book were excellent. Both Camden and our suspect were so smart and it was fascinating to read about each puzzle or clue that Camden took apart.
-I loved this team! Shooter and Cassie were both lots of fun and I hope this series goes on to have more from them as well.
-This book had me on my toes the whole time and for at least half of it I was on the edge of my seat.
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4.5⭐️⭐️⭐️⭐️💫 I thoroughly enjoyed this book and am really hoping this turns into a series.

Book Review: Head Cases by John McMahon
⭐⭐⭐⭐

I really enjoyed Head Cases by John McMahon! It was super interesting and hard to put down. The story pulled me in right away and made me feel like I was watching an episode of Criminal Minds.

The characters were great, and the twists kept me guessing. The writing was easy to follow but still exciting, and I loved how the story kept building the suspense.

I’m so happy I got an ARC of this book! If you like crime stories with a lot of action and surprises, you’ll love this one. It’s definitely worth reading!

4.25 ✨

Thank you St Martin's Press/Minotaur Books and Netgalley for sending me an advanced copy in exchange for my honest review!

I absolutely love police/detective procedurals. Once I read the blurb for this, I knew I wanted to read it! It didn't let me down. Special Agent Gardner Camden is a part of a small team within the FBI - he's neurodiverse, brilliant, and can't help but be blunt. I love this guy. We got so much detail and I realized it's because Gardner is so detailed - the way the author wrote this was perfect because it really allowed us to understand the inner workings of Camden's brain.

Gardner and his team (who I really enjoyed getting to know) are assigned to a case when DNA links a murder victim to a serial killer that's been dead for years. A second victim turns up and thats when Gardner has to come up with a pattern. But then the murderer starts targeting Gardner and his team 👀

This was such a quick read and even more exciting: a show is in development with MAX! I'll definitely be tuning in and I hope we get more of Gardner and his team.

Neurodivergent detective characters have become a trope recently, but author McMahon doesn’t make his Special Agent Gardner Camden a gimmick. It makes sense that the FBI would have a Patterns and Recognition Unit and that its staff would have unusual skills, including eidetic memory and an outstanding ability to amass, analyze, and interpret information—like Gardner has.

The PAR team is called in when a serial killer they thought long dead is found murdered in a way that mimics how he treated his victims. As they investigate this murder, more murders of serial killers occur and the team is off at a breakneck pace to try to crack the case and bring down the “Mad Dog” killer, as they nickname him.

Gardner has a great backstory, and the members of his team are appealing too, though less fleshed-out in this first book. The book blends clues and solutions well with thrilling action and suspense, making it tough to put down, especially once you reach the second half.

John McMahon is an author new to me, but after reading this standout thriller, I want to look for his three P. T. Marsh books, and I look forward to his second Gardner Camden/PAR novel.

Head Casss follows the main character, Gardner Camden a member of a specialized unit of the FBI. The Patterns and Recognitions (PAR) unit is group of FBI unique agents with advanced expertise. The group of agents follow a serial killer hunting serial killers who taunts the agents. Leaving clues along the way. The plot was a complex game of cat and mouse between the FBI and the subject. Head Cases is intriguing and will hook the reader from the beginning.

Gardner Camden is a member of the Patterns and Recognitions (PAR) unit, a specialized group of FBI agents with advanced analytical and technical expertise. Camden, who is neuro-divergent, is a brilliant investigator but struggles with social interactions. When a serial killer believed to have died in a house fire seven years ago in Florida is found murdered in Texas, the PAR unit is called in. As they begin their investigation, another serial killer is found dead. Camden is appointed to lead the team once it becomes evident that the murderer has acquired inside information about the serial killers and is taunting the FBI. Could the murderer be an FBI insider acting as a vigilante? 

Head Cases is the first book in John McMahon's new series featuring the fictional FBI PAR unit, a team of "oddballs, rejects, and weirdos," as they are often referred to behind their backs. The plot is cleverly crafted, with the murderer leaving clues that only brilliant minds can decipher. I thoroughly enjoyed the cat-and-mouse action. Perfect for fans of CBS-TV's Criminal Minds. Sign me up for Book 2. 

(Note - I was initially on the fence in reading this book but because I had downloaded The Minotaur Sampler, Volume 13, I was able to read the first few chapters, and it was all I needed to choose this book. Very glad I did.)

Rated 4.25 stars.

This was such a good police procedural. It had engaging characters (loved the MC), it had a twisted, gruesome mystery, it was suspenseful and had a lot of action (perfect for a movie adaptation).

The PAR unit of the FBI (Patterns and Recognition) is a group of outcasts. Every one of them has their own story of why they were assigned to the team. The main character, Gardner Camden, is an analytical genius and can easily solve puzzles. Unfortunately, he doesn't have keen social skills and sees most things as black-and-white... but that just makes him a quirky character that you can easily root for. He does have a soft spot for his 7-year-old daughter Camilla and his mother, who is in an assisted living facility in Texas..

When a man is murdered, he comes up in the FBI database as a serial killer everyone thought was dead. Including Camden, who was the agent chasing him years ago. But now he's dead? Then when another serial killer is found dead, Camden and his team start to see a pattern emerging. The victims are also covered in weird clues. Can Camden and his team solve this one before the killer strikes again?

This book had such a good balance of character development, mystery, suspense and action. It pulls you in and makes you want to keep reading. If this is indeed a series, I'm definitely reading the next one.

I don't usually love police procedurals, but this one struck me as one that I would really enjoy watching as a show or series.

It is a good one for fans of Criminal Minds. The story didn't entirely stand out to me as unique because of how many police procedural dramas I have seen, but I enjoyed the characters and the ride.

Interesting premise - a serial killer targetting serial killers. This has a dry Joe Friday - just the facts feel and I couldn't get into the groove.

Briefing
Case File #001: Gardner Camden and the PAR Unit
Summary:
This book introduces the enigmatic Patterns and Recognition (PAR) unit of the FBI—a misfit team tasked with solving cold cases. When a presumed-dead serial killer is murdered, and similar victims surface, the team finds themselves in a race against a mastermind who is leaving riddles behind.
Operatives:
• Gardner Camden: Code-cracking genius, emotionally distant but fiercely dedicated. His analytical precision is both an asset and a liability.
• PAR Unit:
• A sniper with a sharp aim and sharper wit.
• A mathematician who sees patterns in chaos.
• A tech whiz who uncovers truths in data.
• A career agent holding the team together under mounting pressure.
Mission Notes:
• Strengths: Riveting plot, cleverly designed puzzles, and a cast as flawed as they are brilliant.
• Challenges: Themes of justice and morality demand readers question their own sense of right and wrong.
• Outcome: An electrifying debut that leaves the door wide open for more cases in thus new series!
Status:
Head Cases is an unmissable first book in what promises to be a thrilling series. Recommended for those who like their mysteries twisted and their protagonists even more so.
Next Steps:
Secure a copy (comes out 1/28/25) and prepare to lose yourself in this web of intrigue.

<i>Thank you to Netgalley and St. Martin's Press | Minotaur Books for the free digital ARC provided in exchange for an honest review.</i>

This book was a propulsive, action-packed adventure. FBI Agent Gardner Camden is a brilliant, quirky detective (a la TV faves like Will Trent, Monk, Columbo... the list goes on). He's eccentric, but self-aware and trying to fit in. I appreciated the care McMahon took in crafting this main character, but also the care he took in creating a supporting cast that makes space for Camden's eccentricities.

While I anticipated many of the twists, I remained engaged in the story and enjoyed the inevitable reveals.

My biggest issues with the book--and these might be due to the ARC and have been addressed in the final version going to print--are SPOILER ALERT:
<spoiler>Camden says "Shooter and I boarded the plane in El Paso" but earlier in the book he said Richie would be going to Texas with him. Was it a simple typo or was there a significant rewrite and the name wasn't updated accordingly? There were also timing inconsistencies: In chapter 4 McMahon said it was "Forty-three degrees at 5:52 a.m." yet in the same chapter notes that "Even at two in the morning, Frank didn't have a curl out of place." And later in the book, Banning's car was shot and disabled in a shootout, but Camden says they just cleaned it off and drove out in it.<end of spoiler>

Given I read an ARC, I'm making an allowance for these errors. However, if I read a final copy and these appeared, it would frustrate me enough to abandon the series (and perhaps DNF the book) altogether.

I want more!

I loved Gardner Camden, our main character. He’s smart, quirky, and stands out as unique in this oversaturated thriller genre.

The murder mystery is complex and keeps a steady pace throughout. The story is well plotted and easy to follow, but there are lots of pieces and you need to pay attention in order to put together the clues.

I alternated between listening to the audiobook and reading my Kindle copy. Will Damron does a fantastic job with the narration. He fully inhabited Camden’s character in a way that felt honest and real.

I’m so excited that HEAD CASES is the first in a series!

*Thanks to Macmillan Audio for the free audiobook download, and to Minotaur books for the free eARC, provided via NetGalley!*

A book about serial killers with a main character who has difficulty with social situations and an eidetic memory? Sign me up! I started out listening to this book but then wanted to finish it sooner so got out my kindle and finished it up in a couple hours.
This book follows the PAR team at the FBI. A rag tag group of misfits as they race to solve a case that they can’t get ahead on.
I honestly loved every minute of it! Can’t wait to read the next one.
I received an ARC of this title, all opinions are my own.

The head cases are a group of FBI agents that specialize in Patterns and Recognition (PAR)
When Gardner Camden, one of the PAR unit, is called to a crime scene, he finds out that the deceased man is a serial killer that he found at a crime scene seven years ago. Now he’s on the hunt for the serial killer that kills serial killers.

This book was narrated by Will Damron who did so well 👏🏻 the story immediately sucked me in, and I had a great time listening / picking up my e-arc at times I couldn’t listen.

This one is for fans of David Ellis and James Patterson! I love a good police procedural with quirky characters and this one delivered.

Thanks so much to NetGalley, St Martin’s Press for my ARC and Macmillan Audio for my ALC.

Pub date 01.28.25

LOVED LOVED LOVED!!!! And am so excited that there will be at least one more book in this new series!!
McMahon's writing is exceptional and these characters he's created for this series, the "misfits" of PAR unit, are so amazingly relatable that I fell in love with all of them, especially Agent Gardner Camden. Loved getting into his head and reading how he thinks and reacts to things.. Loved the storyline, the twists.. I just could not get enough!! Bravo John McMahon! I'd give it more than 5 stars if I could!!