Head Cases – PAR Unit #1

Author: John McMahon
Genre: Crime Thriller
352 pages
Publisher: Minotaur, 2025

Synopsis
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 readers on the edge of their seats and a thoroughly engaging ensemble cast, John McMahon’s Head Cases is a triumph.

My review
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!

Many thanks to NetGalley, Minotaur, and John McMahon for an advance copy to review. All opinions are my own.

My recommendation: definitely worth the read!