Name: Head Cases
Author: John McMahon

Head Cases marks the start of a highly engaging new crime thriller series from John McMahon, starring a team of genius misfit FBI agents. Read my full review.

Publication: Harper Collins, January 2025

Genre: Crime-Detective, Mystery, Thriller, Action

Head Cases Publisher Synopsis

When a serial killer starts targeting other serial killers, and seems to be one step ahead of the FBI at every turn, only one team of misfits has a chance of stopping him …

Gardner Camden is a walking analytical brain with an affinity for riddles, puzzles, and codes. It makes him the perfect fit for the Patterns and Recognition (PAR) unit of the FBI, a team of five brilliant but misfit agents who are too talented, too extraordinary to fire from the Bureau.

Gardner’s smart, but he’s all business – except for his seven-year-old daughter and occasional visits to his elderly mother, he prioritises his work and justice over everything else, no matter the cost.

A serial killer from one of Gardner’s solved cases, presumed to be long dead, is found murdered, and then soon after, another body with a similar story. The mastermind murderer has left clues and riddles for Gardner and his team – a mathematician, a sniper and weapons expert, a computer analytics specialist, and their leader, a career agent – as they track him across the country. With the threat of PAR dissolving, the team can’t afford to make any mistakes and Gardner must work to solve the riddles before it’s too late.

McMahon’s suspenseful and irresistible thriller confronts the scales of justices in the face of a twisted vengeance plot as this engaging cast of characters works together to stop a misguided vigilante.

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My Review

While not familiar with his highly rated Detective PT Marsh series, I was quick to include John McMahon’s Head Cases in my top picks of the new book releases for January – February 2025. I am a huge fan of stories featuring genius misfits proving their doubters wrong, so this title being described as “Mick Herron’s Slow Horses meets David Baldacci’s The Camel Club” sounded like the perfect read for me.

From the opening lines, McMahon’s writing style felt strong. His lead character Gardner is calm, direct and self-aware; an earnest, reliable narrator. The mutual admiration and respect depicted between he and his FBI partner Cassie, a maths whiz, feels authentic. And, her capacity to challenge him, is an intriguing and endearing dynamic, both on and off-the-job.

“Hella impossible,” a voice came from over my shoulder. I glanced at my partner. Cassie is a petite five foot three but has the propulsive energy of a thousand suns. She also uses the slang of a nineteen-year-old. “Nothing’s impossible,” I said.

In fact, I enjoyed the low-grade ribbing and banter between all the members of this small but gutsy team that others in the FBI refer to as Head Cases — an appealing no-nonsense brand of comradery.

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Through this novel’s layered, at times cryptic, vengeance plot and poignant reflections on Gardner’s past, McMahon explores some gritty philosophical territory, e.g. loyalty to family, the law, and natural justice. The red herrings in this mystery investigation are credible. His depictions of bodies, body parts and violence are not for the squeamish either. But if, like me, you’re a fan of realistic, detail-laden TV crime shows like Silent Witness, then you’ll be in your element.

John McMahon’s Head Cases is a fast-paced, action-packed crime thriller, and very promising start to this FBI Patterns and Recognition Unit (PAR) series. I read this within 2 days and now look forward to seeing what cryptic crime puzzles this endearing character ensemble tackle next, and the scope for personal developments being realised.