Wow what a book. I loved the diversity of the characters and the way the main character’s brain worked. It was truly an interesting read. This book was a genre that has been done lots before but I left this had such a fresh take on the profiler/FBI storyline. I can’t wait for book 2!

5 stars
Expected publication date - January 28, 2025

Thank you, NetGalley and St. Martin's Press, for this eARC for rewiew. All opinions are my own.

The PAR Unit of the FBI (Patterns and Recognition) investigates complex cases. The members of this unit are also complex individuals. The other units refer to them as "Head Cases" due to the kinds of cases they work on and the people who make up the unit. This case appears to be a serial killer whose victims are.....other serial killers. As they narrow the pool of suspects, they start to wonder if he could actually one of their own.

I loved this story, and I loved the characters. I hope to read more books in the future in this series and learn more about these characters. I will also definitely be reading the authors other work.

Thank you NetGalley and Macmillan Audio for sending this book for review consideration. All opinions are my own. When the FBI gets a case no one else can solve, they call in the Patterns and Recognition team. The PAR team has a variety of specialized skills, pulled together for their ability to see what other agents may miss. This is a group of misfits who have experienced failures on other team, which has put them in the crosshairs of FBI leadership. Their latest case has also put them in the crosshairs of a serial killer. Will they find the killer before leadership shuts them down? Acclaimed author John McMahon returns with Head Cases - the debut of the new PAR Unit series. Known for the PT Marsh detective series, McMahon latest work has already been optioned by HBO Max before it's even hit shelves! This is a book about leaning into strengths others may see as weaknesses, but also a realistic look at how loss impacts each of us differently. With mystery, drama, and relatable characters, this book will keep you engaged and entertained the entire way. I give Head Cases 5 out of 5 stars. I connected with the main character and got pulled into the storyline from page one. I enjoyed the mystery and will admit I didn't figure out who the criminal was until the author revealed in later in the book! The only holdback I had on giving this a perfect 5.0 rating was a few slight errors when referencing locations in Georgia. In one specific example, the author references a location of "south of Atlanta". Having lived south of Atlanta all of my life, that typically references locations that are still north of Macon - the location in the book was several hours further south nearly to the Florida border. If you love Karen Slaughter's Will Trent series, Marc Cameron's Arliss Cutter series, or the Jack Ryan books by Tom Clancy, you will love this book! It would also be a great choice for a mystery or crime book club - there is so much to unpack about the main character and the crimes. With gun violence, death, and serious injury, I would direct this to readers over 16.

I’m not one to grab all the procedurals out there, but I dabble when one throws a spark. ⚡️ I love a character who has learned to take a weakness and hone it into a formidable skill set.

Gardner Camden is a FBI agent and a member of PAR (Patterns and Recognition). They may be talented, but each member has been reprimanded for wrongdoing and is on the team as a punishment. Nevertheless, the team is clever and close knit. They have a reputation for solving the cases that leave other teams baffled.

They get called in when a serial killer is found murdered. The kicker is this particular killer was found dead in a fire years ago by Camden. Soon another serial killer is found dead. The team realizes this murderer knows more about the FBI than any civilian should.

How will the team protect each other and their families?

Who is the next target?

In less than twenty-four hours I was wondering how I could be finished with this. My brain never stopped turning over possible scenarios. The PAR team has flaws and strengths that fly off the page in brilliant form. There are no strapping hero stereotypes; these are underdogs that I wanted to root for and understand. I liked spending time with these well developed characters. I’ve been to many of the places and landmarks mentioned and the descriptions were top notch.

The way the plot unfolded was brilliant and it felt like the pacing was timed perfectly.

Well done!! 👏🏻 👏🏻👏🏻

All the stars!⭐️

Many thanks to NetGalley and St. Martin’s Press for providing an Advance Reading Copy for review. These are my unbiased opinions.

Not the story I expected. I thought this was about different FBI cases but was actually a fictional FBI story that was a special group of really smart but unusual agents hunting down a serial killer. Lots of facts and lots of action. It really sped up at the end, and I read the 2nd half in a few days. Great for anyone who likes procedural mysteries!

A group of socially awkward FBI agents are tasked with finding a serial killer who is killing serial killers. I loved the inner workings of the group, but found there were just too many characters to keep straight. Between the agents, victims and family members I didn’t know who I was reading about at times.

I did an immersive read, as I also got the arc audio of this book. Both were excellent. The narration was really intriguing and I loved being able to follow along with the book. I rated both versions a 5 stars.

FBI agent Gardner Camden is called into the case of a recently dead serial killer, that was declared dead years ago. The case takes off when more criminals begin to die in the same way they killed their victims. Camden calls in a special team of agents he knows can solve these murders, each agent specialized in different areas of crime.
This is a fast paced mystery that keeps you guessing until the end is near. I read this book in two sittings because it was such a page turner. It's a great read with plenty of suspense.

Head Cases by John McMahon is a smart, gripping crime thriller that pulled me in from the first chapter. It's a perfect mix of character study and police procedural, with nonstop tension that kept me hooked. I enjoy discovering new authors, and what really sets this book apart is the quirky and incredibly likable FBI team at its heart. They’re a group of misfits who’ve made a few political missteps, landing them in a department that mostly handles cold cases. This time, though, they’re called into the field to tackle a chilling investigation, a serial killer who's targeting other serial killers. The team’s unique dynamic and brilliance make them a joy to follow as they unravel the clues to solve this intricate puzzle. It’s a fascinating ride from start to finish!

McMahon does a fantastic job bringing his protagonist, Gardner Camden, to life. I especially loved how he describes Camden's thought process and the way his brain works through complex puzzles. The key characters evolve throughout the story, with backstories being revealed gradually, never giving away too much at once. The constant plot twists keep the mystery alive, unraveling bit by bit as the truth slowly comes to light.

The story kicks off when a serial killer from one of Camden’s old cases, thought to be dead for over a decade, turns up murdered. Not long after, another body with a similar story appears. The killer has left behind a trail of clues and riddles, challenging the team to keep up as the case takes them across the country. With the future of PAR hanging by a thread, Camden faces a race against time to crack the case before everything unravels.

Head Cases is a fantastic police procedural and a great example of this genre. It's perfect for readers who look for well-paced, non-stop action, solving puzzles, and unravelling mysteries with compelling, realistic, and richly developed characters. I'm excited to know McMahon signed a two-book deal with the publisher and I'll definitely pick up the next installment!

This reminded of how much I love police prodecurals, quirky and brilliant detectives, and lots of tiny details that all have a meaning in the end. Loved it so much, and I really hope this continues as a series. The main character/detective was so real, and had me nearly in tears in one scene where his emotions come to the forefront in such a relatable way. All the stars.

John McMahon has given us an American version of Mick Herron's Slow Horses. Here we have a team of FBI agents with marks on their records and have been assign to a special unit known to other agents as Head Cases. This first installment sets us up with teasers on the histories of an interesting cast of characters that we'll have to read the next book find out more. And we will.

The reader follows along with the main character and observes the action, but we're not given insight as to all the inner working of the investigators. But it still works. There's so much going on that you are still engaged in the case and action that you don't miss the ability to figure out the puzzle as you read. You read as fast as you can just to catch up with the investigators. Or maybe the information is their for the reader and I just missed it as I was caught up in the storyline and didn't also feel the need to crack the case. It's a fun ride.

Sensitive readers should know there's a few scenes with vivid anatomical descriptions.

Perfect for readers looking for a new, fast-paced investigation series with a meta-story that will take several books to dole out the backgrounds of an interesting cast of characters.

One of those books that you know instantly you are going to love, and this book validated that gut feel.

A serial killer murdering serial killers, a nonsocial genius with a didactic memory, and his brilliant mother, suffering from dementia. Reminds me of Criminal Minds and I am here for it!

I really enjoyed the entire book, the little clues to sort out, and the genius of Camden Gardner. It’s my first time reading this author and I’ll definitely be catching his next book!

Thanks to Minotaur and Net Galley for this ARC and John McMahon for a great story

I have been on a detective /FBI kick lately. I was not familiar with the author., but that did it stop me from picking this up.

This is a slightly different take on FBI investigations. This is about a group of agent misfits or contrarians who think and analysis outside of the box. They look for unlikely patterns in solving a serial killer who brutally and strangely mutualates the victims bodies.

I enjoyed this quick read. It is set up to be a series. It will be fun to see how the characters evolve.

Thank you, NetGalley, for an advanced copy.

Thanks to NetGalley and St. Martin's Press for the ARC!

This novel felt as if I was reading the Criminal Minds team taking on Dexter, a serial killer murdering serial killers in grisly fashion. A group of quirky FBI agents from the department where careers go to die, come together under the lead of Gardner, a man who loves puzzles and finding patterns in cases, in a fast-paced police procedural. It was a real page-turner with layers, twists, turns, and some heart (among other organs). At times, the novel felt a little uneven by including moments of depth, that didn't have enough breath to them. Character backgrounds felt a little rushed and glossed over which would have helped the reader connect to them and feel a lot more in those deeper moments.

Overall, did it feel highly original? No. Was it a police procedural we've become familiar with on weekly TV? Yes. Does it make it any less fun? Absolutely not. The plotting was well-done and kept me guessing up to the very end as to why all of this was happening and what the ultimate goal of the murder was. I probably won't remember this book by the end of 2025, but it was still an enjoyable read.

This is a two-book deal for McMahon with the second novel in the series expected early next year and I'm excited to see how our "head cases" in PAR deal with another puzzling case.

Reading this was almost exactly like watching an episode of Criminal minds, maybe like one of the two part episodes. We follow FBI agents that are banished to PAR (patterns and recognition) for not conforming to the societal expectations and politics in the FBI, sort of like a group of Dr. Reids, each with their own pattern based super abilities. The entire book was fast paced and clever, if you even remotely enjoy Criminal Minds this is the book for you. The audiobook was also really well done and the narrator does a great job of embodying the main character. This is listed as the first in a series so I will definitely be continuing.



Thanks to Netgalley, John McMahon, and Minotaur Books for this e-ARC that I chose to read and review

This is the first book I’ve read from McMahon, and as suspense goes it’s a cut above the average. While parts of it were admittedly predictable, for the most part it kept me guessing and held my interest. If you elect to read Head Cases, you will probably figure at least portions of it out as you go along; I certainly did. But it doesn’t all fall into place until near the end of the book, and for me that was a nice change, as the “mystery” is usually pretty much a no-brainer.

Character development for the main protagonist of Gardner Camden was decent, if not extensive, but it was notably shallow for the remaining cast of characters. The reader learns little about Frank and his strange habit of never actually eating during meals with the team, for example, although McMahon makes a point of highlighting it at least three times. A little background is shared about Jo (aka Shooter), but virtually nothing about either Cassie or Richie or the rest of the extended cast. It may well have been my take, but the characters I liked most were among those the reader sees the least (Camden’s mother and his ex-wife), and I’d have liked to have seen more on both. If the author makes it a series, as seems likely, hopefully McMahon delves more deeply into all of these characters.

There were several errors that should have been caught in editing that I saw without really looking: at least one error each in continuity, spelling, and word choice. I tend not to look for such things, and in fact actively try not to see them because they detract from my enjoyment of the book. The fact that these were so readily apparent is probably indicative that the book really needs at least one more good editorial sweep, but hopefully they’ll be resolved prior to release.

Overall it was a quick, fun read, and I’d recommend it to a fan of the genre looking to kill a few hours. It’s a decent addition to the police procedural genre and worth taking for a spin.

Disclosure: I received an ARC of this book from the publisher via NetGalley and am leaving a voluntary review.

Neurodivergent FBI agent Gardner Camden is part of the PAR (Patterns and Recognition) team. He works with a group of equally quirky officers, each with a special skillset. Each has had their issues within the FBI and have been sent to PAR as a last resort. They are the misfits or "Head Cases" of the Agency. Now they are being assigned to work on a serial murder investigation tracking down a murderer of criminals.
This was a fun read. I loved all the team members of PAR and felt that their quirkiness added a levity that the book needed. The mystery runs deep in this book and I loved how it all wrapped up. I'm very excited to read more in this series.
The narrator for the audio book, William Damron is excellent. He is able to give the characters different voices in way that works and also keeps the story flowing.

“Head Cases” by John McMahon follows PAR, the Patterns and Recognition unit of the FBI. Agent Gardner Camden is shocked when a criminal he thought was already dead is discovered murdered. When a pattern emerges of someone doing away with bad men, Camden begins a cat and mouse game with a serial killer who thinks he’s doing the FBI a favor. This fast-paced read is one I couldn’t put down!
I absolutely loved this book. The characters, the plot, everything was hitting the mark for me. When a book reminds me of my favorite tv show (Criminal Minds), it’s definitely doing something right.
While I love a good mystery/thriller, this book also set up a lot of interesting subplots that will keep me wanting each new book in the series (Camden’s daughter, his partner, his ex wife, etc). I’m genuinely sad that this book isn’t out yet because that means I have to wait even longer to see what comes next!
In the end, this book obviously gets 5 stars from me. I was on the edge of my seat from the beginning, and while I wanted to solve the case I didn’t want the story to be over! This team is one I want to stick with for a while and then some.
Thanks to Minotaur Books and NetGalley for an ARC!

I absolutely LOVED this book! I will be this book to add to my collection and also the second book of this 2 part series.
If you are a Criminal Minds, BAU, Spencer Reid fan meets Dexter (without the Dexter gore), then you will enjoy this book. I enjoyed the thrill of the hunt of who and how and the why. I can not wait for the second book of this 2-part series to come out!

My thanks to Net Galley and St Martin s for allowing me to review this arc.

Loved this! Highly recommended! I hope this continues as a series with these characters.

FBI agent Gardner Camden and his team track down a serial killer that kills serial killers. Very intelligent and engaging to read. Good writing. Some graphic parts but really enjoyed.