This was a very quick read. At times I felt myself skimming parts that were very detailed and expert criminalist and over my head.

Sidebar, As a girl from Oklahoma (non-practicing at the moment) I really enjoyed the mentions of OKC.

3.5 stars rounded up. This book sort of felt like a procedural law enforcement show in book form. I haven't really decided if that's a good thing yet. It was an entertaining, fast-paced read overall. I see that it's the first in a series. I would put the sequel on the maybe/slightly interested part of my TBR list.

I read an ARC of this book from NetGalley. All comments are my own.

I really enjoyed this!! The head case team is really cute and interesting! The plot kept me hooked and I was not able to figured out the mystery. I saw a second book was coming out and I will be reading! 4.5 stars

I thought that the premise of this book sounded interesting but it was reviews comparing it to the television series CSI that had me itching to pick it up. This turned out to be a really fast paced read that instantly hooked me. Gardner Camden was an interesting main character to read about. Actually his entire team that he worked with was unique with their own strengths and skills. Gardner himself thought was definitely a unique entity. The way that Gardner's mind worked through everything was very interesting to read about. The mystery behind who was behind the killings kept me guessing the entire time. I flew through the pages of this one, and am excited that this is going to be a series so I have more books with these characters to look forward to.

Readers looking for a fast paced, intense read need to give this book a try. If you enjoy books like UNSUB by Meg Gardiner or Killing Floor by Lee Child, definitely pick this book up. This author has another series that I want to try now while I wait for the next book in this series to be released. Four stars for this book and I'm eager to read more by this author.

Head Cases is a smart, fast-paced crime thriller that deftly blends tension, intricate puzzles, and a compelling team dynamic. John McMahon has crafted a cast of quirky yet capable agents who bring both expertise and unexpected camaraderie to the story. FBI Agent Gardner Camden stands out, written with authenticity, being equal parts brilliant and emotionally reserved. His struggles were relatable and his victories satisfying. I love a good crime thriller with great characters and an even better plot.

The premise of a serial killer targeting serial killer's was genius and executed well. The plot really hooked me with the creepy riddles that felt like they were written just for Gardner. The investigative details were great, enough forensic grit to feel real, mixed with plenty of twists and thrills, and just the right amount of dark, chilling moments.

Head Cases is an engaging, cerebral thriller that delivers high-stakes suspense and meaningful emotional depth. McMahon’s blend of mystery, procedural rigor, and character warmth makes it a compelling debut for the PAR series. The pacing was spot on, and the twists are so well-executed that I never saw them coming. It offered enough thrill to leave me eagerly awaiting what Gardner and his team do next. I absolutely recommend this one!

Thank you NetGalley and St. Martin's Press for the ARC in exchange for my honest review.

If you like Criminal Minds, especially the new Evolution series, you will enjoy this book. It’s also reminiscent of Slow Horses and Dept. Q, British shows about groups of misfits solving serious crimes. I particularly enjoyed the main character, Gardner Camden’s neurodivergent traits. I’m so glad this is the first book in a series!

Themes of redemption, trust, and the impact of trauma permeate the narrative, encouraging readers to reflect on the complexities of the human mind. McMahon artfully illustrates how past experiences shape behavior and relationships, creating a nuanced portrait of mental health challenges.

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!