Head Cases by John McMahon is an unpredictable thriller about the hunt for a serial killer whose mission is to kill the bad guys. The FBI has a team of investigators that can solve the most difficult cases and (my new favorite character) Camden is chosen to lead. He's great at solving puzzles and piecing together the meaning behind clues but he's not as great at reading social cues or filtering his comments.... which makes him the funniest-without-meaning-to-be, most original character I've come across in forever.

When the suspect contacts Camden and takes his threats to a personal level, the race to find Mad Dog intensifies and it's all FBI hands on deck. The fact that Camden isn't sure who not to trust makes things even harder because the rookie on his team has questionable credentials, the head of the FBI has made questionable decisions, and Camden's mind is working overtime to figure it all out.

I'm beyond grateful to NetGalley for the ARC of Head Cases and even more grateful that this is the first book in the series by John McMahon. I can't wait to see what Camden and his brilliant mind take on next....

When I delved into John McMahon’s Head Cases, I was immediately drawn into a labyrinthine narrative that masterfully intertwines psychological depth with relentless suspense. This novel introduces us to the FBI’s Patterns and Recognition (PAR) unit, a team of uniquely skilled agents tasked with deciphering the most perplexing cases.

At the forefront is Special Agent Gardner Camden, an analytical genius whose prowess in solving intricate puzzles is juxtaposed with his challenges in navigating human relationships, including those with his colleagues and his cherished seven-year-old daughter, Camila. This dichotomy adds a compelling layer to his character, making him both formidable and relatable.

The narrative gains momentum when DNA evidence links a recent murder to Ross Tignon, a serial killer presumed dead for years. As the body count rises, it becomes evident that the perpetrator is not only targeting serial killers but is also orchestrating a macabre game, leaving behind cryptic clues specifically designed to challenge Camden’s intellect. This cat-and-mouse dynamic propels the story forward, with each revelation intensifying the stakes.

The novel’s pacing is meticulously calibrated, with McMahon deftly alternating between high-octane action sequences and introspective moments that delve into the psychological toll of pursuing a cunning adversary. The tension is palpable, and the plot is replete with unexpected twists that kept me continually reassessing my theories about the killer’s identity.

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

I requested “Head Cases” because I’ve always been a big Criminal Minds Spencer Reid fan. And that’s basically what you get with “Head Cases” by John McMahon. Gardner Camden is the socially awkward FBI agent with an eidetic memory who spits out random facts as he struggle with social interactions like Spencer Reid . Instead of the BAU you have the PAR. The PAR however normally investigates cold cases but during the story they are forced into the field as a killer they thought had died years before turns up dead.
I normally just read romance but this book caught my eye and I’m glad it did. The pacing of the story was great. I never got bored. The plot kept me turning the page to find out what happened next. This fulfilled my Criminal Minds/Bones cravings in book form.

Head Cases features a specialized unit within the FBI who are called in when an investigation hits a dead end. The Patterns and Recognition unit (PAR) is comprised of a small group of agents who have unique abilities to solve puzzles and find new threads to pursue to solve stalled cases. Other agents often derogatorily refer to PAR as Head Cases. It’s unusual for the PAR agents to work in the field, but when a serial killer who was declared dead years ago is identified as the victim in a recent murder, the unit is sent to investigate. Before their investigation has really even begun, there’s another murder and they must quickly put all the clues together to stop the vigilante. This is a thoroughly entertaining story that has an interesting cast of characters and a storyline that will keep you engaged until the final page is turned. If you enjoy FBI/police procedurals or programs like Criminal Minds, NCIS, CSI, or Bones, you’ll enjoy reading this book.

This book was EXCELLENT! I absolutely love FBI & serial killer plot & this one was great. I thought the plot was fast paced & unique. I enjoyed the twists! & I really loved meeting the characters…the Head Cases! I could see this being a great movie or even series! I look forward to more books in this series!

This book is about a case that is being handled by the FBI Unit known as PAR. Each of the individuals in the unit has made some sort of error. This is one of the 1st times they have been in the field since they usually only deal with files for Closed Cases. This instance they are working on a case where the victim is someone who supposed several years earlier. The leader on this case is being led by Gardner Camden, who was involved with a case where the victim was supposedly burned alive.

The victim of this case was a serial killer that the FBI was closing in on when his body was found burnt many years earlier. There is not a lot of evidence for this and before they really get involved, Gerald receives another call advising him of a body that was discovered in New Mexico of another serial killer who had just be released from prison. In a short while when Gerald went to view the autopsy of the 1st victim, he received a call which was from the killer. This call referenced another killing in Calif. that was similar

Gerald figured out that the killer was obtaining information from an FBI source. He finally nailed it down to one individual who had logged into specific files. This individual was highly placed and immediately cleared. With the login information, they tried to lay a trap to narrow the location where the killer was at. A specific location was identified and a team was sent to arrest this person. Gerald made arrangements to be on site.

Gerald finally got the killer angry and Gerald's family was threatened. He made arrangements to keep his daughter safe but forgot about his mother. The mother was attacked an as a result of Gerald's action, he was suspended. Gerald convinced Frank to help him out. Gerald came up with who the killer was and Frank went to capture him while Gerald was to go home. Gerald still was working out how to locate the killer. The location was identified and Frank went to make the arrest. Things did not go well.

To learn who the killer was, what his reason for killing the people was, what event forced the killer to seek revenge and how it all worked out in the end, then you need to read this book.

Head Cases introduces us to a specialized FBI team (PAR) that is called in on cases that have stalled, for their expertise in patterns, mathematics and data. We are introduced to one of the agents, Gardner Camden, who is great in his position, but like the others on the team, were relegated to this behind-the-scenes department due to missteps in is his career. Camden is a likeable character who is aware of his flaws, making him transparent and human to the reader.

The PAR team is called to a case where a serial killer is found murdered. The twist is this serial killer supposedly died in a fire years ago and was an old case of Camden. Soon, other murderers are murdered, and the team must find out who is behind the crimes. What makes the case even more intriguing are the politics inside the FBI, when it is obvious that the killer knows things that are only contained in the FBI case files.

I enjoyed this debut series and the characters that were developed in the book. There was a good pace as the clues led to the killer and also revealed other secrets and agendas in the FBI leadership. I recommend this book and look forward to future installments.

Thanks NetGalley and Minotaur Books for the advanced copy

This book was so good! It felt very cinematic. The story was twisty and left you questioning everyone in it. I enjoyed the references to the past cases, the peaks into the lives of the main character AND to know the life was not perfect. It was a fast book that kept me wanting more! Highly highly recommend.

Thank you to NetGalley, Minotaur Books and the author for the opportunity to read an ARC of Head Cases, scheduled for release on January 28, 2025. Discovering a "new to me" author is fun; discovering a great writer is bliss. I discovered a great writer while reading Head Cases by John McMahon. Head Cases is the first, in what I hope will be a long running series, featuring Gardner Camden and the FBI Patterns and Recognitions Unit. The Unit in this story is comprised of Frank Roberts, Unit director, Cassie Pardo, a mathematician, Joanne "Shooter" Harris, a former Olympic sharpshooter, Richie Brancato, a recent grad and number one in his class at Quantico and Gardner Camden, a man with an eidetic memory. The unit was often considered as the nerds, head cases, socially inept agents; thus they worked research, not actively in the field. Another point of interest, each of the members had something in their professional past that diminished their light in the eyes of FBI leadership, with the exception of Richie Brancato, yet his personnel file was sealed.. It was certainly a surprise when Gardner Camden and Cassie Pardo were called to Texas to investigate a murder. Could the victim be Ross Tignon, a series killer the FBI believed had been killed years before in a house fire? While completing that assignment, they are called to New Mexico to investigate the identity of another viciously murdered seriel killer, Barry Fisher. Could it be possible that a seriel killer was murdering seriel killers? Head Cases is a finely crafted thriller with such a well developed plot and characters that I couldn't put it down. The Unit members came alive on the pages as well as the support characters including Gardner's mom, daughter and the national FBI director. Head Cases also explores the politics, the pride and the integrity that drives some agents and former agents as well as illustrating the pursuit of excellence at all costs by some. I am anxiously looking forward to the second book in this series, hopefully in 2026 according to the author. Kudos to John McMahon for this new series; I highly recommend Head Cases. This review reflects my honest opinion. 4.5 stars.

“Head Cases” by John McMahon is a suspense thriller. It’s the first book in the “PAR Unit” series which is a group of secretive FBI agents hunting a serial killer that was thought dead. This is an exciting new series with enjoyable characters.

ɴᴇᴛɢᴀʟʟᴇʏ ʀᴇᴠɪᴇᴡ || HEAD CASES [thank you to @minotaur_books and @netgalley for my #gifted copy!]

Title: Head Cases
Author: John McMahon
Genre: Suspense, Thriller
Format: Digital
Star Rating: ★ ★ ★ ☆ ☆

ꜱᴜᴍᴍᴀʀʏ:
FBI Agent Gardner Camden and his team of brilliant misfits must crack a killer’s deadly riddles—but as the murderer closes in on their personal lives, the stakes become terrifyingly personal.

ᴍʏ ᴛʜᴏᴜɢʜᴛꜱ:
This book was a wild ride - if not, ultimately, like watching an episode of tv that isn’t my favorite but gets the job done.

If there’s one thing that I like about Spencer Reid, it’s that he generally walks you through how his brain comes to a conclusion - & that was missing here. 🤷🏻‍♀️

I always prefer it when I’m able to try to follow the dots myself, rather than having the author tell me what the dots are. So that was a miss for me. But this was a quick, easy read if you’re looking for an escape!

ʀᴇᴀᴅ ɪꜰ ʏᴏᴜ ʟɪᴋᴇ:
Criminal Minds
Police Procedurals
Mindhunter
Zodiac
Fast-Paced Mysteries

ᴅᴇᴛᴀɪʟꜱ:
GR: 4.25 ⭐️
# of Pages: 352
Pub Date: January 28, 2025

3.7 Stars
One Liner: Entertaining but don’t think too much about it

FBI Agent Gardner Camden is an analytical genius and one of the four super-talented agents at the PAR (Patterns and Recognition) unit. Of course, this comes at the cost of human emotions, something he fails to achieve even with his seven-year-old daughter.
When the DNA of a new victim reveals he was recorded dead seven years ago, Gardner is called to investigate the case (along with his team). A second death occurs, starting a pattern they need to break to stop the killer from committing more murders.
However, things are complicated, and the killer knows a lot more about PAR and its members than they do. Can Gardner and his team solve it before their lives are in danger?
The story comes in Gardner’s first-person POV.

My Thoughts:
The premise screams high competence coupled with wonder kid-type talent which made me want to read the book. The 4-star reviews by friends sealed my decision. Despite the flaws, I don’t regret reading it. In fact, I want the series to be longer than two books (with the hope that the flaws get addressed).
The initial 30% is slow despite starting with the murder. We also get details about the team members and teeny backstories. The foundation is laid, so makes sense that the pacing dips. The second half was pretty fast for me. It sustained the momentum with reveals and twists. Is some of it a bit too convenient? Yeah, it is but still fun.
Each member of the team has a distinct ability and a reason for being in PAR, and the reasons aren’t always good. While this adds some layers to the characters, there isn’t enough to turn them into strong personalities. Gardner gets better profiling since he is the MC and the voice of the book. His personal life is rather interesting, something similar yet different to what we tend to see in the genre.
The police procedural part was cool, especially since we have these competent fellas working on the same. They are still human - make mistakes, miss clues, and even go in circles. But hey, you can notice they are good at what they do.
The MC likes to share random insights and facts. Since this doesn’t get excessive, I liked how it added to his personality. Don’t bother about connecting with him or others. It’s not likely that we will. Think of it as a TV show (Criminal Minds maybe) in book form.
The MC’s mother has a short yet important role. I hope she will be featured in the next book too. His daughter is certainly interesting but we don’t see enough to get an idea. Of course, she’s just a sweet seven-year-old.
Naturally, there are office politics but it doesn’t overpower the central plot. It is woven into the mystery and provides a smooth landing for the ending and maybe a lead for the next book.

To summarize, Head Cases is an entertaining novel if you like FBI-style police procedurals with highly talented characters. While it has a few issues, there’s no denying that I enjoyed the book and look forward to the next one.
My thanks to Steve Erickson, NetGalley, and St. Martin’s (Minotaur Books), for eARC. This review is voluntary and contains my honest opinion about the book.

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.