Detective P. T. Marsh Reading Order
| Title | Published | Buy on Amazon |
|---|---|---|
| The Good Detective | 2019 | Buy |
| The Evil Men Do | 2020 | Buy |
| A Good Kill | 2021 | Buy |
Head Cases (PAR Unit) Reading Order
| Title | Published | Buy on Amazon |
|---|---|---|
| Head Cases | 2025 | Buy |
| Head Cases: A Novel | 2025 | N/A |
| Inside Man | 2026 | Buy |
John McMahon writes crime fiction with a Southern setting. His first series follows Detective P.T. Marsh, a Georgia detective dealing with personal demons while investigating violent crimes. The Good Detective (2019) launched the series, which continued with The Evil Men Do (2020) and A Good Kill (2021).
His second series, Head Cases, shifts into different territory with a Paranormal Activity Response unit. The first book arrived in 2025, and Inside Man is expected in 2026. McMahon worked in advertising before turning to fiction, and his background in storytelling shows in his tightly plotted thrillers.