I honestly love detective lead thrillers and this one was so much fun. A serial killer, hunting serial killers? Sign me up. Gander Camden was such a fun character, as were the rest of the PAR Unit. I loved how because of their uniqueness, they got their own department in the FBI. The twists in this book amazing and the pacing was great. I am so excited this is the first book in this series, so we will get more!! The audiobook was also amazing and really added a lot of character to the story.

Someone is playing vigilante and killing serial killers. The first one was a man about to be indicted for three murders when his house caught fire and a body assumed to be him was found. That was seven years ago and he had been free to roam the country and continue his killing spree until the new killer found him. The second case was a killer who had just been paroled after decades behind bars.

PAR is the Pattern And Recognition unit of the FBI. Gardner Camden works in the unit, sharing with the others some miscue in his career that didn't warrant dismissal but made it better if he was forward facing with the public. In his case, it was turning in his beloved wife when he found she and her boss were defrauding a bank, giving his partner, a respected FBI agent and her father, a heart attack. In others, it was disrespect, hitting on the wrong woman, or other mistakes.

Everyone in PAR has a unique talent. Gardner has an eidetic memory and sees patterns where others do not. His partner, Cassie, has the same pattern sensing ability but more on the mathematical side. Another woman is an Olympic level sharpshooter. Frank runs the unit and focuses on the big picture. Gardner is on the spectrum and the only person who really understands him is his mother but she is now hospitalized with dementia.

To his surprise, Gardner is put in charge of the case, going over Frank's head. Gardner was the person who had identified the first killer seven years ago and the Director feels that he would have an advantage on finding the killer who believes his mission is to kill other killers. As the case progresses, it becomes evident that the killer knows much about Gardner's life and that his plan is to also kill off prominent FBI members. Can Gardner find him?

This is the first book in a new series by the author, who works in marketing when not writing thrillers. He has another series also. In this one, the pace is fast and furious, perhaps a bit too frantic but quite engaging. I'm looking forward to seeing where the PAR unit goes and more of Gardner's life. I listened to this book and the narrator had the perfect voice to move the story along. This book is recommended for mystery readers.

In Head Cases, John McMahon crafts a riveting, fast-paced thriller that keeps readers on the edge of their seats from start to finish. The novel introduces Gardner Camden, an FBI agent with a sharp analytical mind and a knack for solving complex puzzles. While brilliant in his professional life, Gardner struggles with the more human aspects of his work, especially when it comes to his relationship with his young daughter, Camila.

Gardner leads the FBI's Patterns and Recognition (PAR) unit, a team of exceptional individuals brought in to tackle cases that are deemed unsolvable. When DNA links a recent murder victim to a serial killer presumed dead, the team is thrust into a new investigation. As a second victim turns up, the killer begins leaving cryptic clues and riddles designed specifically for Gardner, pushing him to his limits.

Unlike typical FBI units, the PAR team is composed of diverse specialists: a mathematician, a weapons expert, a computer analyst, and a career agent. Each team member must bring their unique expertise to the table as they race against time to solve the puzzle of the killer’s identity. But the investigation takes a dark turn when the team realizes that the killer is somehow always one step ahead, learning more about their every move and threatening not only their lives but their loved ones as well.

Head Cases combines a gripping narrative with intriguing characters, weaving a complex web of suspense, danger, and mystery. McMahon masterfully blends psychological drama with traditional detective work, creating an ensemble of characters that are not only highly skilled but deeply human, each with their own quirks and challenges.

The pacing is relentless, with high-stakes moments that keep the tension high and the plot constantly twisting. As Gardner and his team close in on the killer, the reader is left wondering just how much danger they are truly in, and whether they can outsmart a criminal who seems to be as much of a puzzle as the case itself.

Will Damron's narration elevates the book, with his skillful voice acting bringing the story's characters and high tension to life. His performance captures the psychological depth of the characters and the urgency of the investigation, adding to the overall intensity of the experience.

Head Cases is a standout thriller with clever plotting, well-developed characters, and a compelling mystery. It's a triumph for fans of psychological thrillers and crime dramas, offering a story that is as intellectually stimulating as it is heart-pounding.

Head Cases by John McMahon; unfortunately this one wasn't for me. Not what I expected from the blurb.

Special thanks to the author & @minotaur_books for my gifted copy & @macmillan.audio for the gifted ALC‼️

A serial killer killing serial killer’s count me in. A team full of FBI misfits we’ll call them triple X ban together to find a serial killer. Each agent specializes in something that will help them find a break in the case. Dropping cryptic messages and hacking the FBI’s database the killer “Mad Dog” sends the team on a wild goose chase that would lead them right back to the Bureau.

This was a cool book filled with dark themes and graphic scenes. It dragged a lot in the beginning and middle but I think I really enjoyed it because it reminded me of the movie The Little Things with a mix of Law & Order. This one might not be for everyone but if you like crime fiction/murder mystery you’ll like this book.

Rating: 3.5/5 ⭐️

What a gripping and intelligently crafted read! I was completely drawn in by the dark, clever layers of this atmospheric crime thriller—full of sharp twists and an irresistible game of cat and mouse.

This FBI procedural stands out with its meticulous plotting, unforgettable cast of eccentric, offbeat characters, and a remarkably compelling lead.

A stellar series debut—I’m already eager to see where the PAR Unit heads next. With a television adaptation in the works, I can’t wait to watch this brilliant story come to life on screen.

Excellent characterization, but the plot was a bit over the top.



Review copy provided by publisher.

If you like Criminal Minds, this one will be right up your alley. Head Cases has a cool premise—a quirky team of FBI specialists solving twisted, puzzle-filled murders—and the case definitely kept me guessing. Gardner Camden is a solid lead, even if emotionally closed off, and the killer’s mind games were a highlight.

Some pacing issues and missed emotional beats kept it from being a full hit for me, but overall a strong, clever debut. I’d check out book two!

I listened to the audiobook and Will Damron is one of my favorite narrators, he did a great job like always. This one was interesting! It held my attention the whole way through and kept me wanting more. I read somewhere that this is the first of a series and I hope so! Highly recommend!

Head Cases was an excellent read. The writing was propulsive and the character development was rich. I would read more from this author.

Great first in series! A detailed crime procedural that doesn't read above your head or drown you in procedural jargon.

This is about a special group of the FBI that seems to be made up of outcasts but together form a great team. This group is brought in to hunt a killer who is killing killers. (wow thats a lot of "kills") There is your typical cat and mouse chase of the unsub and particular agent but it works.

The main agent, Gardner Camden, is a genius with zero people skills. He gives you a Sherlockish vibe, seeing things at scene that others may overlook. He thinks in puzzles and is working hard to solve this one as the fate of his unit may depend on it.

I will definitely be on the look out for book 2.

This is a solid police procedural, with interesting characters and a good mystery, I really liked the PAR unit, this has the basis for a great series featuring these agents. Pick this on cup if you enjoy a mystery with a few twists along the way that keep you guessing.

If you know me, you know I love my police procedurals and I’ve been craving a strong detective/police procedural lately. I’ve been looking for something to tie me over until the next Karin Slaughter book comes out, and I think I found a new author to watch for.

The first in a new series, Head Cases follows FBI Agent Gardner Camden and his team the Patterns and Recognition (PAR) Unit as they case a serial killer killing…serial killers. The first victim – one of Camden’s cases from years ago that the FBI thought had died. Can they catch the killer before the case become too personal?

Slow Horses meets Criminal Minds. Plenty of action and a good balance of characters. Camden has neurodivergent tendencies, and I felt that McMahon did a wonderful job of giving him growth but keeping him realistic. I primarily listened to the audiobook and Will Damron was an amazing narrator for Camden. I definitely loved the way this series started, and I can’t wait for the PAR #2. Going to have to dive into McMahon’s P.T. Marsh series next!



Head Cases is out now. Huge thank you to Minotaur Books & Macmillan Audio for my advanced copy in exchange for my honest opinion. If you liked this review, please let me know either by commenting below or by visiting my:
Instagram @speakingof.books.
Tiktok @speakingof.books
Website: SPEAKINGOF.ORG
2 likes

Lost audio before I could finish listening. Was told they’d send a physical but that didn’t happen either so will either have to buy or never read it.

Once I really gave this book a chance, I enjoyed it! I listened to the audiobook version. Will Damron did an excellent job by bringing Gardner to life. I really enjoy quirky characters in books, and John McMahon writes them well. If you’re looking for a good police procedural thriller with a quirky main character, check this book out! Thank you NetGalley and Macmillan Audio for providing me with an ALC in exchange for an honest review.

I do not always read procedurals but as a fan of Criminal Minds like shows, I was curious about this new series. The characters were the best part of the book, their relationships with each other, their personality, their quirks. The storyline was fast-paces and interesting, kept me listening. Will be continuing the series. If you like reading about serial killers and delving into the minds of the people trying to catch them, give this a read.

Listening to the audiobook made the story even more gripping.

Thank you to NetGalley and the publisher for the ALC.

"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!

I listened to the audiobook narrated by Will Damron. As usual, he did an amazing job bringing the story and characters to life. His top-notch narration made this an unpausable listen. He seamlessly transitioned between characters and was able to build so much tension and suspense. Highly recommend this one on audio.

Thank you to NetGalley and Macmillan Audio for the ALC in exchange for an honest review.

I listened to about 10% of the audio and couldn't really get into it, the MMC was a little "off" and I just wasn't gripped from the get-go.

Please circle back to my review for the ebook of this one but DANG!!!! This one was even more spectacular on audio.

Head Cases is my first 5 star read of 2025. This book really drew me in. I love how a group of people who hadn’t played a political game of their career were put together to form the PAR Unit. (Patterns and Recognitions Unit) They were all very intelligent and had their own strengths.

Serial killers being killed?! And little clues hidden along the way?! I felt like I could have been watching an episode of Criminal Minds. The author was able to give enough description to where I could visualize it happening, but not overkill. Now that I’m thinking back over the book, it was a clean read. It just goes to show that books don’t need romance or spice for them to be a great read. There wasn’t even a lot of cussing (which cussing doesn’t bother me, I’m married to a Marine. But it does bother some).

This book had me suspecting so many people. But I didn’t guess any of the twists. This was a quick read that I didn’t want to put down/stop listening to. But I also didn’t want it to end! I consumed most of this book by audio during my work commute. Will Damron has to be one of my favorite male narrators. He voiced Agent Gardner Camden so well. I felt like he really brought him to life. All his little quirks.

I am anxiously awaiting book 2 in this series. It probably won’t be for another year but it can’t come soon enough! I need books from each of the characters.
I think overall, I just throughly enjoyed this. I would recommend it to people who enjoy Criminal Minds or the FBI shows.