Head Cases is book one in the brand new series PAR Unit by John McMahon.
This book was so great - it has a fantastic plot, an engaging and well-developed cast of characters and great pacing.
I was immediately intrigued by the storyline and the complexities in the plot. It kept me captivated throughout the novel.
This book is an intriguing, fast-paced thriller with well-rounded characters and an exhilarating plot.

This was an excellent book. I had a great time getting to know the characters and watching their relationships change. They were an intelligent and interesting group. The mystery was also interesting with little intricacies. I loved how the MC put it together and the reader was privy to his thought process. I did not have this one figured out early on and it was nice to watch it all unfold. It took a moment in the beginning to get used to the writing because the MC is very unique so it felt strange to be in his head, but once I settled in it was a fun ride.

This was my first book by McMahon and I'm so glad I jumped on this series with the first book. I can't wait to see where the team goes from here. I'm already looking forward to the next book in the series.

This was an intriguing mystery that had me guessing. There were plenty of twists and turns and puzzle pieces to fit together. The story came together and wrapped up nicely. I am looking forward to the next installment.

Thank you to NetGalley and the publisher for the ARC of Head Cases by John McMahon. This gripping thriller is packed with tension, dark secrets, and an unpredictable mystery that kept me engaged. McMahon’s writing is sharp and immersive, pulling me into the mind of the protagonist as he navigates a case filled with twists and moral dilemmas. The psychological depth adds layers to the story, though some parts felt slightly rushed or underdeveloped. One flaw that stood out was the pacing—while the book starts strong and keeps the tension high, certain key revelations felt hurried, making it difficult to fully absorb the emotional weight of the twists. A bit more time spent unpacking the consequences of these moments could have made them more impactful. Despite this, the story remains compelling, and Head Cases will appeal to fans of dark, thought-provoking crime fiction.

If you like Criminal Minds, Benedict Cumberbatch's Sherlock, this book is for you! Someone is gruesomely killing bad people. Is it a vigilante or are they doing it for some other twisted reason. The PAR team is run by Camden an analytical genius who loves solving puzzles. This is interesting, I love the team and can't wait to see what they'll do next.

I wanted it to be the Criminal Minds, Spencer Reid, BAU book of my dreams - and unfortunately, it was only okay for me. I felt the pacing was wildly off - so quick at time and other times it dragged with description and conjecture. I didn't love the backstory of our main character - it felt a bit far reaching for something that would, assumingly, have some level of a secret clearance.

At the end of the day, this was just an okay police, detective book - but with all the framework needed to be something better.

Calling all fans of CRIMINAL MINDS! This book is for you. The crimes in this book were twisted, the characters interesting and the plot was good. I'd definitely read more of the PAR team.

What a fun start to a new series! While the plot did feel a little rushed, I really enjoyed the characters and I’m interested to see how they develop in future novels.

Thanks to NetGalley & St. Martin's Press | Minotaur Books for the chance to read this book!

I'm so glad the cover of this book was so intriguing, I am ashamed of myself to admit but I did often judge a book by it's cover and there was something about this one, that was an instant click and request for me! I love series about FBI Groups & this one was done beautifully! It was like reading a REALLY GREAT mini-series of criminal minds, which I've always wanted to do! It feels like you get so much more out of reading these type of things, you get so many more little details. I was a little worried about some of the stuff being over my head, the terminology and all the little fancy words CSI people use but it was actually quite easy to understand and anything you don't they explain expertly.

It was honestly just great, the suspense it made you feel and even the moments you don't normally get to see of these agents, all the sweet little snippets of Camden and his daughter. Very fast paced read for me, and I loved every minute of it! I will def be looking out for the next one in the series and the Author's other books also

Head Cases is 1st book in the PAR Unit series by John McMahon. Not sure why but I never really connected with this book. At times I found it to move really slow, and I didn't seem to like any of the characters in the book. Having said that I am sure many will really enjoy this book so for that reason I would recommend it to others.

I received and ARC from NetGalley and St. Martin's Press, and I am leaving my review voluntarily.

I really enjoyed this one. While maybe the storyline isn’t that astounding but the characters make for such an entertaining read! This is set up to be one a great series and I’m hoping for that. Thanks to the publisher and netgalley for this copy for read and review

This crime procedural book easily captured and kept my attention. Focused on a special unit of the FBI in charge of cases no one else can solve, it immediately made me think of Criminal Minds and was a great listen,

As the PAR unit hunts for a killer who is offing serial killers, they trek back and forth across the country, having meetings aboard private jets and sending different members to different locations. It is fast paced, action packed, and adrenaline filled. The characters are unique, with interesting individual skill sets that make them an unstoppable team when put together.

This was a great start to a new series, and I will absolutely be ready to read the next installment.

The audio was narrated by one of my favorites, Will Damron. He does an incredible job navigating all of the characters, the building tension, and the action packed moments.

Thank you to Minotaur for the gifted arc and Macmillan Audio for the audiobook. All opinions are my own,

5 stars! If you liked ‘Mindhunters’ on Netflix, you will love this book. It starts off fast and keeps up that pace. I read/listened to this book in 24 hrs, it was that good!

I’m a sucker for anything that can mirror the thrills I get from watching Criminal Minds on television. Head Cases came very close to that I must say. It was action packed, full of shocking and bizarre criminal behavior, along with a cast of lovable, relatable characters. It was quite busy moving from location to location that I sometimes had to stop and figure out where the drama was unfolding, but overall I think this was a great series starter.

Solid story, good suspense, interesting characters. Excellent misdirects, which are important in a mystery/thriller. Not a new idea as such but well executed and it definitely kept my attention: stayed up way too late on my second reading day and then picked it up again immediately when I woke up too early the next morning. I’ll definitely read the second book in the series when it comes out.

Only quibble: some of the poisoning information is incorrect - but I only know this because I worked in toxicology for 8 years. I doubt it’s going to matter to to most readers.

I liked this FBI investigative novel, mostly because of the quirky characters. Each agent has been placed in this unit because of some previous unacceptable behavior. Each one has some unique ability, such as an eidetic memory or amazing sharp shooting skill, and they work through this case differently than a traditional team. Their expertise involves pattern recognition so their methods are as unique as they are. The banter between the agents was entertaining.

I had mixed feelings about the lead character, Gardner. He was so sure of himself, every time they got a new clue he was quick to conclude this person was their villain. I would have preferred he have a more open mind as he was wrong, until the last one. It was irritating.

The plot was suitably complex as it involved past crimes and present people in the FBI. We got a good sense of the politics within the agency as the agents go about their unusual ways to solves the murders. I do like McMahon's writing style and will be watching for the next book in this series.

I received a complimentary egalley of this book from the publisher. My comments are an independent and honest review.

PAR Unit #1. The PAR (Patterns and Recognition) Unit is a special branch of the FBI staffed with analytical geniuses who do not see the world as ordinary people do but gifted with skills to solve puzzles and see outside the box. When DNA results in a recent homicide come back as belonging to a serial killer thought killed in a fire years ago the unit is called in. Subsequent deaths cause the team to believe they are searching for a vigilante with a mission to hunt down criminals who somehow escaped justice. This investigation will take them out of their usual working behind the desk situation into the field as leads send them across the country. Agent Gardner is an isolated self contained protagonist who must get more in touch with his human side to coordinate his team and follow leads. The supporting cast of characters are quirky and diverse yet committed to justice. The story line is compelling and dramatic with unique conflicts and twists that keep the momentum moving at a fast pace. The forensic and investigative details seemed to be authentic. I have long been drawn to FBI thrillers especially those relating to serial killers and I found this premise of a special branch to be fresh and engaging. This is listed as #1 so I am looking forward to the next adventure from this group of talented detectives and am eager to learn more of their back stories. I enjoyed the interaction as the newly formed team learned how to work together and play on each others strengths. If you enjoy a tense and dark crime novel this is one to dive into.

This was such a great book! From the first chapter, I was hooked. It definitely felt very much like Criminal Minds both in the characters and the story.

Head Cases is a twisty police procedural that was like putting a puzzle together. Everything slots into place bit by bit until the full picture becomes clear.

I'm thrilled that this is going to be a series. Gardner, as an analyst, was a wonderful character. His memory recall and pattern recognition skills were a great asset to this story. This was a fantastic start to a new series and I can't wait for the next installment.

I received a complimentary copy of this book. Opinions expressed in this review are my own.

I really enjoyed listening to this. The narrator was the perfect choice for this. He sort of gave me Joe Kenda vibes. Head Cases is the perfect book for those of us who love to watch police procedural and detective shows. I think it would also be great for true crime readers who want to stay close to the genre but take a break from real crimes! I myself am a true crime lover at my core, but I also really love thrillers and mystery. This sort of blends those loves for me, while not a true crime case it definitely feels like it could be at times.


Overall, this was a brilliant story that kept me interested and on the edge of my seat. I was even shocked by many of the twists. I can't wait to see where this series goes. I'm definitely going to be eagerly awaiting book twos release.

I received a copy in exchange for an honest review.

This was my first novel by John McMahon and he will now be an author I look for! A group of FBI agents are hunting down a murderer that is seeking his own justice. This novel kept me on the edge of my seat the entire time. I would highly recommend.