Head Cases

A Novel

By: John McMahon

Narrated by: Will Damron

Head Cases follows an enigmatic group of FBI agents as they hunt down a murderer seeking his own justice in this electrifying—and commercial—series debut.

FBI Agent Gardner Camden is an analytical genius with an affinity for puzzles. He also has a blind spot on the human side of investigations, a blindness that sometimes even includes people in his own life, like his beloved seven-year-old daughter Camila. Gardner and his squad of brilliant yet quirky agents make up the Patterns and Recognition (PAR) unit, the FBI’s hidden edge, brought in for cases that no one else can solve.

When DNA links a murder victim to a serial killer long presumed dead, the team springs into action. A second victim establishes a pattern, and the murderer begins leaving a trail of clues and riddles especially for Gardner. And while the PAR team is usually relegated to working cold cases from behind a desk, the investigation puts them on the road and into the public eye, following in the footsteps of a killer.

Along with Gardner, PAR consists of a mathematician, a weapons expert, a computer analyst, and their leader, a career agent. Each of them must use every skill they have to solve the riddle of the killer’s identity. But with the perpetrator somehow learning more and more about the team at PAR, can they protect themselves and their families…before it’s too late?

With an enigmatic case that will keep listeners on the edge of their seats and a thoroughly engaging ensemble cast, John McMahon’s Head Cases is a triumph.

A Macmillan Audio production from Minotaur Books.

©2025 John McMahon (P)2025 Macmillan Audio

Critic reviews

“In this suspenseful cat and mouse thriller, Camden balances brilliance with a deeply flawed awareness of social cues, retaining the edge of a compelling protagonist. This, combined with McMahon's gripping plot, will pull readers in.”—Booklist

“McMahon introduces several clever wrinkles to this classic cat-and-mouse setup, while making the socially awkward Camden and his colleagues three-dimensional enough to sustain future installments. With pulse-pounding action and enough surprises to blindside even seasoned mystery fans, this is an excellent start.”–Publishers Weekly (Starred review)

"Head Cases begins as a riveting story about the hunt for an apex predator—a killer of serial killers—but quickly becomes so much more: the only road back to what’s left of one man's family, friendships, and identity. It’s a taut, thrilling read.”—Jess Lourey, Edgar-nominated author of The Taken Ones

Pleasantly surprised

Great mystery book with a really good plot. First time i listened to this author. I’ll definitely be checking out more of his books.

Tight and gripping storytelling

Really enjoyed the twists and turns in the story. All the characters were engaging and surprisingly fresh. The performance did the story justice.

Great story and plot.

I liked it all. The story was entertaining and held my interest. The details didn't bore me.

Clever misfit FBI agent

Clever misfit FBI agent who is Gary of a special group tasked with solving strange cases. It starts with trying to solve the milder of someone previously declared dead. The victims were all serial killers meaning specialties knowledge would be needed to track them. The solution was a surprise.

Loved this! Great new series!

Great new series and a new author for me. I'll be looking nti his other work and am looking forward to book 2 in this series. The characters are well written and had a great rapport with one another.

Slow moving

This is usually my favorite genre but I found this book a bit draggy and slow moving. I couldn’t relate to any of the main characters and the autistic detective was hard to like don’t think I will give this author a second chance

Not my usual brew but...

I loved this book. I was intrigued, surprised, revulsed, and it made me laugh several times! Great book! I hope this continues into a series!

This one is a WINNER!!!!

Since I’m already a fan of John McMahon’s P.T. Marsh mystery/procedural novels I already had a feeling that I was going to enjoy this book. Add to that Will Damron’s narration and you have a sure winner! I’m a huge fan of Will Damron and wish he would do more in the mystery/thriller genre.

This book is a great cat and mouse procedural. The hero (Gardner Camden) is in an FBI unit made up of agents who have all made some kind of major f**k up in their careers but are otherwise exceptional at their job. His nemesis is playing games with him and feeding him puzzles only he can figure out. Being an expert at puzzles Camden feels it’s his responsibility and his sword to bear for every death. Even though the serial killer he’s hunting is killing other killers. And with each kill he leaves a new clue somewhere on or in the body. Some only centimeters, so nothing is obvious. The climax is just as good as the rest of the story and the ending is open for future books if this is to turn into a series. One can only hope!

This book has my VERY HIGHEST RECOMMENDATION!!

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Perfect for True Crime Junkies!

If you’re a fan of true crime and crime dramas you’ll love Head Cases. A unique blend of an underdog story mixed with a group of misfits with unique skill sets and abilities makes this an interesting read.

As the agents of Patterns and Recognition (aka PAR) investigate a series of murders that at the beginning, didn’t appear to have a connection soon reveal insights into federal law-enforcement agencies, bureaucracy, team dynamics, and the shortcomings of those who believe that they’re above the law.

Agent Gardner Camden, described as an analytical genius with an affinity for puzzles, is a great main character. Throughout the narratively, not only did we see his keen ability to solve cases we also get a glimpse into the depth of his character as an individual through his willingness to assimilate and be like those around him, the love of his family and his relationships with counterparts on the job.

Secondary characters (Cassie & Shooter were my favorites!) stood out and added a unique layer of personality to the narrative.

The pace of this novel is slower than I typically enjoy reading, but the pace matched the narrative perfectly. I’m a big fan of “whodunnit”/true crime/serial killer novels and this one checked all the boxes for me. Looking forward to the second in the series!

Love Gardy!

Main character is easily likable. I hope there are sequels with him. He grows on you. I did like the story line as well. I do like this author, very original stories.