I just want to sum of this book with words:

Quirky, Thrilling, Nerdy, Serious, Funny, Shocking, Gripping, well thought out, well written.....so many feelings about the book and all of them good!

Loved reading it, couldn't put it down, stayed with me long after I was done and hope that there is another one following!!



Many thanks to NetGalley and St. Martin’s Press/Minotaur Books for sharing this digital review copy with me in exchange for my honest thoughts.

Head Cases by John McMahon is a thrilling ride into a group of PAR misfits who have specially unique gifts. Camden, with his photographic memory, Richie who can run analysis on situations and circumstances to give probable statistics that actually help, as well as the rest of the team really kind of reminds me of the BAU unit from Criminal Minds. Hits hard and keeps you guessing as you follow the clues along until the very last page. LOVED IT!!! Will definitely be on the lookout for this author and future works.
*I received a copy of this book from NetGalley. This review is my own opinion*

Head Cases is one of the best procedural thrillers I've read in a long time.

A bunch of people who are looked down on by their coworkers for their differences - for how they far too quirky in other people's eyes, when in reality they are some of the most hardworking and thoughtful people there.

And they are put onto a case where DNA found at a crime fits that of a serial killer that has been presumed dead for years; now they are struggling to figure out how they've been wrong and why has the killer come back out of hiding.

Gardner is a good team lead, you can see his passion for the job, even as he struggles with how he can't be there for his daughter Camilla as he wants to, making promises of how he will one day be able to move closer to her and her grandmother, be more present in her life after her mother is no longer able to be.

HEAD CASES by John McMahon is an engaging police procedural about a special department of the FBI whose current task is to hunt down a killer murdering famous serial killers.

Police procedurals are mostly boring to me but this one was the opposite of boring. It had the right mix of characters, quirkiness, mystery and puzzle-solving to keep me hooked throughout.

Recommend to a friend? Yes, friend, read it — especially if you love Criminal Minds (the TV show) since it reads like an episode of Criminal Minds.

PS: I love this cover.

Head Cases by John McMahon is a fun, clever thriller that feels like Criminal Minds if the BAU team had even more weird brainiacs and a whole lot more emotional baggage. The story follows FBI agent Gardner Camden, who leads an ultra-specialized unit called PAR. Each member has a niche superpower-level skill—math genius, weapons expert, hacker vibes—but they all work together like a dysfunctional, lovable family.

When a murder connects to a supposedly dead serial killer, the team hits the road to investigate, unraveling a string of eerie clues that seem tailor-made to mess with Camden’s head. There’s plenty of action, cool forensics, and just enough humor to keep it from getting too dark.

The characters are fun and unique, the plot moves fast, the twists are solid (even if a couple feel a bit convenient), and the team dynamics give major Criminal Minds energy—with just a little more heart and weirdness.

Not perfect, but definitely entertaining and I am looking forward to this being (hopefully) a longer series. If you're into profiling, crime puzzles, and misfit geniuses chasing killers, this one's worth checking out.

This was a great read! I love the way Gardner thinks and how unique his character is as well as the team as a whole. The whole case came together very well and I was shocked by the twists. Its amazing how some peoples mind works and we see that with the PAR team as well as the author for being able to write a story like this.

First thank you to Minotaur books and NetGalley for an e-arc in exchange for an honest review

⭐️⭐️⭐️⭐️⭐️

Synopsis: Gardner Camden is part of a group of agents that looks for patterns and insights in the data to solve crimes. They get called out to a crime sciene where the victim a serial killer they thought was dead is found dead. Soon another serial killer is found murdered and the group enters into a game with the new serial killer. Will they be able to solve the crime in time?

What I liked: this book was amazing and kicking myself for not reading it sooner. Sometimes I get the opposite of fomo and won’t read a hyped book due to fear it won’t live up to the hype. This one did not disappoint. I loved all of the characters but especially Gardner and shooter. The rookie was great as well. I loved how they all had some kind of political misstep that landed them in the unit. This was such a great cat and mouse game too. I stayed up way past my bedtime to read it. No spoilers but the twists were perfect and not too many plus the ending was great. I can’t wait to read book 2 and this time I will not wait.

𝗥𝗘𝗔𝗗 𝗜𝗙 𝗬𝗢𝗨 𝗟𝗜𝗞𝗘
✷ Serial killer thrillers with a twist
✷ Audiobooks you can finish in a day
✷ Procedural mysteries with high body counts
✷ Antiheroes toeing the morality line
✷ Fast-paced stories over deep character arcs

𝗧𝗛𝗢𝗨𝗚𝗛𝗧𝗦
This one had such a solid concept — a serial killer who only targets other serial killers? Yes, please. I was immediately intrigued by that premise and expected something dark, twisty, and a little bit subversive. And while Head Cases delivers on the action and the pacing, it didn’t quite stick the landing for me overall.

I listened to this on audiobook and finished it in a single day. The narrator did a good job keeping the momentum going, and it’s definitely a binge-worthy listen. But despite how quickly I flew through it, I never really connected with the characters. They all felt a bit flat or interchangeable, and even the lead didn’t leave a lasting impression. I wanted more emotional depth — something to make me care beyond just the clever setup.

The plot itself leans heavily on procedural tropes, which isn’t necessarily a bad thing, but it started to feel formulaic after a while. I kept waiting for it to surprise me — to dig deeper into the psychology or subvert the genre — but it mostly stayed in safe, familiar territory.

That said, if you're looking for a fast-paced thriller with a cool hook and don’t mind sacrificing character depth for speed and style, this could work for you. For me, it was entertaining in the moment but ultimately forgettable. I’m still undecided on whether I’ll continue the series.

4 stars. Read in a weekend. Thought the ending was slow and I skimmed some, otherwise would have been 5 stars. Glad to see he's got book 2 coming out next year.

Head Cases is a crime novel with a team of FBI agents trying to stop someone who is executing his own brand of justice by murdering people who were criminals themselves. While the agents follow clues and apply all their skills, the suspect seems to stay one step ahead of them. Is there someone inside the FBI helping the perpetrator? How did he find a victim that the FBI thought had died several years ago?

The story is mostly told from the perspective of the lead agent who is single and somewhat socially awkward. He remembers everything and while this is his first case he heads up, the other team members follow his leadership unquestioningly.

Pick this one up if you like a mystery with a quirky main character and don't mind a bit of adult language!

Five stars for one of the smartest FBI books l've read.
These "head cases" are super intelligent officers expert at solving puzzles. You're just along for the ride. Excellent book. Already looking forward for the next.

A gripping thriller that introduces the FBI’s PAR unit- a team of misfit s tasked with solving cases too complex for traditional methods. The protagonist is Gardner Camden with a supporting cast of characters with quirky charm and sharp skills. A great read.
Many thanks to St. Martin’s Press and to Netgalley for providing me with a galley in exchange for my honest opinion.

This was a fun read. I dove headfirst into this read thinking it was a non-fiction novel, but it is not. It's about an odd group of FBI agents, all of whom share a love of solving riddles. They're brought in to solve the cases that no one else can solve. They call themselves the PAR (Patterns and Recognition) unit. Gardner, the featured agent, "is an analytical genius with an affinity for solving puzzles." Add a mathematician, weapons expert, a computer analyst, and a career agent to the mix, and you've got PAR.
PAR lands a case when DNA links a murder victim to a serial killer who the FBI had thought was long dead. A second murder occurs soon after, thus a pattern is established. Following along as the team works to solve the case was so captivating, I even found myself thinking about the story when on walks with my dog. The focus is mainly on Agent Gardner, who I suspect is on the autism spectrum, given his inability to read social cues easily, his keen ability to identify patterns and trivia facts to solve the case, and his blunt approach in communication.
This is book #1 of the PAR Unit series, so I am anxious to see what comes next.

Thank you to Netgalley and the publisher for my advanced egalley!

I requested Head Cases because the premise sounded good. What I got was a new author who can write a captivating FBI thriller. The characters belong to a unit called PAR. This unit is made up of agents who have had less than stella careers with the bureau but have the brains and fortitude to solve a cold case.
The characters are so real and the procedures they followed seemed very true to what I would expect the FBI procedures to be. I enjoyed the plot of a serial killer ridding the world of bad people.
I look forward to the next installment of the PAR series.
Thank you NetGalley and St Martin’s Press for my ARC in exchange for my thoughts.

This was such an enjoyable read. I read this over a few weeks, dipping in and out and loved the way the story progressed. I thought the PAR group had just the right mix of characters amd personalities on there team and of course I love a good crime novel.

I thought the author did an excellent job of weaving together this story and giving just pieces of clues away to what was happening. I really enjoyed the focus on the process of finding the killer and not so much what the killer was doing. I thought it made me more engaged trying to follow their trains of thoughts, along with the oddities of the main character.

I am definitelt looking forward to reading the next book im the series!

Head Cases is a procedural series opener featuring an ensemble unit of FBI special agents written by John McMahon. Released 28th Jan 2025 by Macmillan on their Minotaur imprint, it's 352 pages and is available in hardcover, audio, and ebook formats. Paperback due out from the same publisher in 1st quarter 2026. It's worth noting that the ebook format has a handy interactive table of contents as well as interactive links throughout.

The interactions among the specialists on the team (mathematician, weapons expert, sniper, computer IT, and the requisite neurodivergent main guy) is engaging and well written; lots of banter and interplay. The author's style is direct and unvarnished, and surprisingly effective.

The second book in the series is due out in 2026. Readers who enjoy psychological/FBI type procedurals will likely enjoy this one.

Four stars. It would be a good choice for public or home library acquisition. Some rough language and graphic content, but nothing egregious for the genre.

Disclosure: I received an ARC at no cost from the author/publisher for review purposes.

“𝗦𝗼𝗺𝗲 𝗽𝗲𝗼𝗽𝗹𝗲 𝗱𝗼𝗻’𝘁 𝘁𝗮𝗸𝗲 𝘁𝗵𝗶𝗻𝗴𝘀 𝘀𝗲𝗿𝗶𝗼𝘂𝘀𝗹𝘆 𝘂𝗻𝘁𝗶𝗹 𝘁𝗵𝗲𝘆 𝗵𝗮𝘃𝗲 𝘀𝗸𝗶𝗻 𝗶𝗻 𝘁𝗵𝗲 𝗴𝗮𝗺𝗲.”

𝗣𝘂𝗯 𝗗𝗮𝘁𝗲: 1/28/25

𝗦𝘂𝗺𝗺𝗮𝗿𝘆: Four FBI outcast agents form a PAR or patterns and recognition team, chasing down a serial killer who is killing serial killers. Main character, Agent Camden finds himself in a twisty cat and mouse game.

𝗛𝗶𝗴𝗵𝗹𝗶𝗴𝗵𝘁𝘀:
🫆 Police procedural
🕵🏻‍♂️ Thriller
🫆 Cat and mouse
🕵🏻‍♂️ Neurodivergent representation

𝗠𝘆 𝗧𝗵𝗼𝘂𝗴𝗵𝘁𝘀: For lovers of true crime documentaries and TV. This gave me CSI vibes with a mix of Dexter. I loved the cast of characters all with their own special talents. This was a well written police procedural thriller.

𝗥𝗮𝘁𝗶𝗻𝗴: 3/5 ⭐️⭐️⭐️

*Thank you @NetGalley and @StMartinsPress for sending this book for review consideration. All opinions are my own.

#HeadCases

This book hit a spot for me and I’m officially a John McMahon fan!

I will be reading any PAR unit books from here on out.

Thank you for the opportunity to preview Head Cases. This is a police procedural novel that centers on an elite FBI group and a lead investigator.
I think this will be a series as although this novel is wrapped up at the end there Is certainly enough interesting information about this FBI group to provide more cases.
There’s a lot to digest and follow in this case of a murder and a supposed defunct serial killer.
Great detective work is outlined and a lot of characters to follow.
If you enjoy the intricacies of detective fiction this is a good read.
3.5 stars

Thank you so much to netgalley and the publisher for the arc of this one in exchange for an honest review!

This book follows a FBI agent who is part of the PAR unit. He is very smart and a bit different than most people. The whole unit is full of people who have special skills but are not necessarily the best socially.

In this book, we follow a case that involves a serial killer who kills serial killers and taunts the police. We follow the team as they try to catch the killer.

I really enjoyed this book! I loved all the unique characters and situations that they were in. The investigation kept me guessing throughout.

I wanted to be an FBI agent when I was little so this book was right up my alley. If you like Criminal Minds or investigation books, this one is for you!

I can't wait to read the next book when it comes out next year!