Most thriller writers have to research police work. LaMorinda author Adam Plantinga has spent more than two decades living it.

Plantinga is a sergeant with the San Francisco Police Department, a career that has given him an unusually close view of human behavior, danger and the split-second decisions that can change everything. It has also provided rich material for a writing career that began with nonfiction and eventually led him into the world of fast-moving crime novels.

The path was not entirely unexpected. Plantinga grew up in a family of readers and studied English in college, but writing initially took a back seat to police work. Over the years, he began collecting the practical lessons, observations and hard-earned knowledge that rarely appear in training manuals. Those insights became his first book, 400 Things Cops Know, published in 2014.

The book earned Agatha and Macavity Award nominations, won the Silver Falchion Award for best nonfiction crime reference and found an enthusiastic audience among readers and crime writers. Plantinga followed it with Police Craft, a collection of essays exploring homicide, crime scene investigation, SWAT and other specialized areas of law enforcement.

Fiction gave him a different kind of challenge.

His 2024 debut novel, The Ascent, introduced Kurt Argento, a former Detroit police officer with a strong moral code and very little ability to ignore injustice. The book became a USA Today bestseller and was optioned by Universal for television. Plantinga continued Argento’s story in Hard Town, released in 2025.

Now Argento returns in Dark Country, the third novel in the series, arriving Oct. 27.

Following the violence of Hard Town, Argento has disappeared into Barton, South Dakota, where he is working under an assumed name as a church handyman. His quiet existence ends when he encounters Majed, a 17-year-old Syrian refugee being pursued by two men. Argento steps in, soon discovering that the situation is far more dangerous than it first appeared.

What follows is a tense road trip west as Argento attempts to protect Majed from people willing to kill for whatever the teenager may know or possess. The story delivers the action readers expect from the series, but its heart lies in the unlikely connection between a man trying to disappear and a young person searching for safety.

Plantinga writes while continuing his full-time police career, often opening his laptop whenever his schedule offers a pocket of time. His years in law enforcement give his books their authenticity, but the characters and moral questions keep them from reading like police reports.

At home in Lamorinda, Plantinga and his wife are raising two daughters who stay busy with local school and club sports. He has even joined a bocce league, although police work does not always cooperate with the match schedule.

Dark Country will launch Oct. 27, with an appearance planned at Book Passage in San Francisco and additional local events under discussion. Moraga readers may also have an opportunity to hear from Plantinga closer to home as future library and community programs take shape.