Thank you for the ARC.

This book read like a movie. Felt like the movie Seven or the show Mind hunters. I could picture all the details and was pulled into the storyline. I liked how the story built off all the parts found by the detective. The murders were just enough gore, but not too much. I would for sure read more in this series.

If you're a true crime lover, you will love this gritty FBI novel. When cold cases are dug up, you never know what will be revealed! This book is dark and twisty, sometimes graphic, but definitely puts you inside the heads of both the killers and the FBI agents who try to tackle their cases.

John McMahon has a winner with Head Cases, the first book in the PAR Unit series. Filled with unusual characters hunting down a murderer seeking his own brand of justice, the FBI’s Patterns and Recognition (PAR) unit is generally tasked with solving cold cases. The team consists of five misfit agents led by Frank Roberts, but the main character is Special Agent Gardner Camden.
A serial killer from one of Gardner’s solved cases, thought to be dead for more than a decade, is found murdered. Soon, there’s another similar case. The killer has left clues and riddles, but can the team solve them?

Gardner is intelligent, confident, all business, and has an eidetic memory. He thinks in terms of layers and patterns, avoids friendships with most, and can come across as arrogant. He has an affinity for riddles, puzzles, and codes. I enjoyed how the author brought to life both the personal and professional lives of Gardner. As readers learn his background, it provides insight into his thoughts, behaviors, and actions. It was fascinating to see how Gardner’s mind worked to solve the various puzzles.

Frank is a career agent and the other members include a mathematician, a sniper and weapons expert, and a computer analytics specialist. The secondary and tertiary characters are reasonably well-drawn for the first book in the series and I would expect the repeat characters to gain more depth as the series progresses. It was also delightful to see how this team of supposed misfits worked so well together.

I was immediately intrigued by the storyline and the complexities in the plot. It kept me captivated throughout the novel. It was fascinating to see the story unfold. Full of suspense, this thriller looks at justice through the eyes of Gardner, but readers also get a feel for the antagonist and the vengeance that is sought.

The conflicts move the story through some twists and turns as the story gradually builds momentum and finishes with some surprises and an action-packed finish. The novel also illuminated the politics that can go on behind the scene for agents that don’t fit the traditional mold.

Overall, this was a compelling and dynamic story with excellent characterization, good pacing, and a great plot that includes solid procedural details. I can’t wait to read the next book in the series which is expected in 2026. Those who enjoy crime thrillers and FBI investigations with extraordinary characters as well as those who enjoy solving puzzles will likely enjoy this novel.

St. Marin’s Press – Minotaur Books and John McMahon provided a complimentary digital ARC of this novel via NetGalley. All opinions expressed in this review are my own. The publication date is currently set for January 28, 2025. This review was originally posted at Mystery and Suspense Magazine.

Head Cases introduces readers to the Patterns and Recognition (PAR) unit, a brilliant and unconventional group of FBI agents tasked with solving cases no one else can crack. Led by analytical genius Gardner Camden—whose affinity for puzzles comes with a blind spot for the emotional nuances of human interaction—the team faces their toughest challenge yet when a string of murders ties back to a long-dead serial killer.

As the case escalates, the murderer leaves riddles and clues specifically for Gardner, pushing the PAR team out of their usual cold-case investigations and into the field. With their unique skills, the agents must uncover the killer’s identity before he strikes again...and potentially at them.

This book is perfect for fans of FBI dramas or profiler-based shows. The structure of the investigation and the twists along the way reminded me a lot of Bones—you know the obvious suspect isn’t the real culprit, but piecing together the how and why keeps you turning the pages. The case was intricate, and the dynamic among the PAR team added depth to the story.

It did take me a bit of time to adjust to the writing style, but that’s often the case for me with books in this genre. Once I found the rhythm, I really enjoyed the mix of suspense and intellect.

Overall, Head Cases is a promising start to a series that blends clever puzzles with a thrilling investigation. If you love ensemble casts, intricate mysteries, and high-stakes drama, this one’s worth checking out—even if it’s outside your usual genre, like it was for me!

This is how a police procedural should be done! This is Dexter meets Criminal Minds. A killer that hunts killers. Is it for revenge, notoriety, or something sinister? We have a neurodivergent FBI agent, a former Olympian turned FBI sharpshooter, a rookie shrouded in mystery, and others all coming together to catch a monster. So well well-written and easy to read. Not a dull moment ever from page one. I will be reading everything this author has released in the past as well as all future books.

What a wonderful surprise this book (first in a series and looking like a natural for TV turned out to be. In summary, it eels like a been-there concept — quirky FBI dude is part of a team of misfits investigating, in this case, someone killing serial killers. But I was really taken with McMahon’s hero, Gardner Camden, and his crazy focus on solving this convoluted crime. Reviewed in print and online for the St. Louis Post-Dispatch on Jan. 12.

For fans of Criminal Minds, Mind Hunters, and NCIS. This book follows Agent Camden and his very lovable team of the FBI's Patterns and Recognition department as they set out to solve a case (previously thought to be solved) of a serial killer who is killing serial killers. Which sounds pretty straight forward, but I assure you, there is quite the journey uncovering what motivated the killer and who they are.

This book had me engaged the entire time. Parts of this story had my heart racing. Other parts had me near tears. I'm looking forward to the second one!

Thank you to NetGalley and St. Martin's/Minotaur publishing for the opportunity to read this.

A interesting new detective series. I have been on the hunt for a new long time series and this book is a good prospect. I have been reading Karin Slaughter and Pat Cornwell for ages and this ranks up there.

A quirky detective, a team full of misfits...makes for the perfect crime solving team. I was invested in the main character and my only criticism being that the neurodivergent eccentric detective role. It's been done more than once ranging from Criminal Minds to Monk. The writing was decent and the story well written so I can forgive that. Would have been better done if the author had let the reader come to that conclusion, not making it so obvious. I do appreciate the twist at the end. Don't want to give spoilers.

I would read the next book in this series.

A good first outing in a new series from John McMahon, featuring an FBI agent named Gardner Camden who is 'somewhere on the spectrum' and is part of a team nicknamed Head Cases because, while they have 'good heads for cases,' they are also oddballs in different ways.

Gardner takes the lead on their current case and it's a weird one--it appears someone is targeting serial killers. The temptation is to say 'Have at it!' but of course they need to find and stop this killer and boring them to justice.

Very interesting characters, especially Gardener who is telling this story in first person. It's fascinating to see how his mind works and puts information together. He is so smart but often so clueless about human interactions.

Many thanks to the author and publisher for providing me with an arc of this new suspense thriller. This was my first taste of McMahon's books and I look forward to reading more. My review is voluntary and the opinions expressed are my own.

“Head Cases”, the first novel in the new PAR Unit series by author John McMahon, follows FBI Agent Gardner Camden. Gardner is a member of a special team within the FBI called PAR, Patterns and Recognition. PAR basically consists of the freaks and geeks of the FBI who are especially skilled but also more than a little anti-social (even neurodivergent).

One day a wild case comes across their desks – the murder of a serial killer who they thought died a long time ago amidst their investigation of him. But that’s just the first in a string of similar crimes and their search for the killer (or killers?) will take the team all around the country.

This is the kind of book that grips you from the first page and will have you stay up reading till 2 AM just to see what happens next. The pacing of the novel lends itself perfectly to TV so I was thrilled to hear the TV rights have already been sold.

This book is perfect for fans of TJ Newman, “Criminal Minds”; or those who are fascinated with serial killers and mile-a-minute crime procedurals.

It isn’t a read that I’ll be thinking about for years to come but it so much fun, I anticipate it will be *the* mystery/suspense/thriller of 2025, and I can’t wait for the next book in the series and eventually the TV adaptation!

3.5 rounded up. Thanks to NetGalley and the publisher for an ARC in exchange for my honest review. I enjoyed this first book in a series about a section of outcasts within the FBI. It was somewhat reminiscent of the team from Slow Horses and I look forward to future installments.

This is a compelling new FBI/police procedural series for fans of Criminal Minds, solving puzzles, and unraveling mysteries. The PAR unit of the FBI, also known as the Head Cases, are made up of a brainy, nerdy talented crew of misfits who use their strengths to solve cold cases. I loved following along and trying to solve the case along with them. This novel focuses on catching a killer who is targeting serial killers - a perfect, compelling plot (who doesn’t love a great serial killer thriller!) The main narrator is slightly neurodivergent- he has a sharp mind but is less adept at social interactions. Because he is the one to introduce us to the other characters in the book, I did find the character descriptions to be repetitive and one dimensional (we get in depth descriptions of each characters clothes and what they are eating multiple times in the book). Other than that, I really enjoyed this one and look forward to reading the next in this series and getting to know these characters more.

Thank you to NetGalley and St Martin’s Press for an advanced reader copy in exchange for my honest review.

Wow! Head Cases was one of the best police procedural thrillers I have read in a long time. I truly enjoyed taking the ride with the special FBI unit assigned to catching a serial killer. This book took many twists and turns and I stayed up way too late to finish it! I highly recommend it to all readers who enjoy the show Criminal Minds or books with puzzles.

Thank you NetGalley and Minotaur Books for sending this book for review consideration. All opinions are my own.

Gardner Camden is an FBI agent in the PAR unit (Patterns and Recognition). He sees patterns in crimes that others do not see. When he is called in to find someone that is killing serial killers, he must work with his team to figure out who is leaking information and see the patterns in the killings before more people die.

I really liked this FBI/ police procedural. It was fast paced and intricate but not so much that it was twisty. I liked the characters a lot and thought it was a good balance of plot and character building. This is clearly going to be a series a will definitely continue reading it.

Thank you to Netgalley for the advance copy for review.

I think I have a new favourite series and I honestly can’t wait until book 2 whenever that may be because this one doesn’t even come out until the end of the month 🤦‍♀️
If you are a fan of Criminal Minds ( or similar series) you will love this one ! Hard to put down suspense & action ; quirky but lovable FBI agents and a serial killer … well more like a few!

My rating 4.5 ⭐️

John McMahon’s Head Cases is a gripping FBI thriller that will keep readers hooked from start to finish. With its complex characters, a brilliantly twisted killer, and a narrative that maintains tension throughout, this book is a standout in the crime thriller genre.

The story centers on FBI Agent Camden, whose unique perspective and emotional detachment make him an unconventional protagonist. While his personality might not resonate with every reader, it’s precisely this trait that makes him compelling. His ability to think differently becomes a vital asset in the pursuit of a diabolical killer, and McMahon expertly weaves this into the narrative. Camden’s struggles with feeling “different” add a layer of depth to the story, making him more than just a typical crime-fighting hero.

The writing style is sharp and immersive, with McMahon skillfully building suspense and delivering unexpected twists. The antagonist is chillingly well-crafted, keeping the FBI—and readers—on edge throughout. The pacing is spot-on, with each chapter driving the plot forward without feeling rushed.

For those who enjoy audiobooks, the Audible version comes highly recommended. The narration enhances the story, drawing listeners deeper into the world McMahon has created.

In summary, Head Cases is a masterful blend of psychological depth, thrilling action, and a cat-and-mouse game that will leave readers guessing until the end. Highly recommended for fans of crime thrillers who appreciate a unique protagonist and a plot that keeps them on their toes.

This gripping series opener follows a team of exceptionally intelligent but quirky FBI agents in the Patterns and Recognition (PAR) unit. Told from the perspective of Agent Gardner Camden, the story centers on a serial murder investigation that begins with the unexpected reappearance of a serial killer presumed dead for years. As the agents become entangled in the killer's intricate web of clues and puzzles, the future of their unit—and their careers—hangs in the balance as they race against time to catch the elusive murderer.

The book is a compelling read, masterfully written with engaging, well-developed characters and a perfectly paced narrative. The tension steadily builds, culminating in a thrilling conclusion. The author skillfully plants subtle clues throughout the story, keeping readers on their toes and constantly questioning which details are important. Camden, the protagonist, takes note of numerous intricate details, inviting readers to join him in piecing together the mystery. The intriguing premise sets the stage for future installments, with a sequel already scheduled for release in 2026.

A series launch focused on a group of quirky but extremely intelligent FBI agents in the Patterns and Recognition unit (PAR). Narrated from the perspective of Agent Gardner Camden, the book follows an serial murder investigation starting with the death of a serial killer who was presumed dead years ago. The agents quickly get drawn into the killer's web of clues and puzzles, and the future of their unit (and their jobs) depends on catching the killer in time.

This was an excellent book. The book was well written, the characters were all interesting and well-developed, and the pacing was perfect--steady and really picked up at the end when everything comes to its conclusion. The author drops subtle clues about the case, yet still keeps you guessing the entire time. The main character constantly notes lots of details so you as a reader are trying, along with the characters, to suss out what's important and what's not. The premise was intriguing and the book is set up perfectly for a sequel (coming in 2026).

Highly recommended for fans of Criminal Minds.

Thanks to NetGalley and the publisher for the ARC in exchange for an honest review.

The Patterns and Recognition (PAR) Unit of the FBI is headed by Gardner Camden, whose unique way of looking at the world helps him to solve the hardest riddles and puzzles. Cassie Pardo is the numbers and statistics expert, Joanne "Shooter" Harris knows everything about weapons, and new agent Richie Brancato is a wild card. The PAR Unit is where agents go for their careers to die. Even other agents refer to PAR as the freaks, misfits, and weirdos. They've been called in on this case to prove their worth to the FBI. Can they find the vigilante taking out serial killers? Or will they fail and have the unit disbanded?

This was slow to start, I wasn't sure I was going to finish it. Once the mystery was set up and they started trying to track the killer, the pace sped up. I thought I knew early on what the twist would be, but I wasn't anywhere near being right. Camden is definitely a little different, possibly autistic although that's never stated. The interaction between the agents shows a close relationship and understanding of each other's strengths.

All in all, this was a solid mystery filled with puzzle pieces and intrigue. If you like a detective novel where the killer is playing a game with the police, then this is for you!

Thank you to @Minotaur_Books and @NetGalley for a digital copy for review consideration. All opinions are honest and my own.

The oddball PAR team of the FBI is tasked to solve the case of a serial killer whose victims are all serial killers. PAR has a computer analyst, a weapons expert, a mathematician and is lead my a career agent - all who have pissed off internal FBI agents at some point in their career (which is how they ended up in PAR). This new serial killer is learning about the members of PAR and going after them as well to make sure he/she’s not caught.

This one totally gave me Department Q vibes (a Danish noir series about a ragtag department working in the basement solving cold cases) - I loved the non conformists working in PAR and am very excited that this seems to be the first in a series. I had both the audio and ebook of this, but got so caught up in how well the narration was for the audiobook that I barely read this one and simply listened. This was well written thriller and kept me engrossed the whole time as the team chased the killer. Head Cases came at the perfect time for me since the Department Q series just ended.

Thank you to Minotaur Books and NetGalley for the ARC to review