Steve Cavenagh’s “Thirteen” is a unique take on the popular genre we generally label the “police procedural.” But here, that label is not an exact fit. For one thing, it’s not the police who do the investigation. It’s a lawyer, the fascinating Eddie Flynn. Eddie is an ex-con artist who has become a terrific criminal defense attorney. As such, he not only helps people rather than cheating them, he also gets to use those old conman skills when the appropriate occasion arises.

Like all good fictional protagonists, Eddie is no angel. His checkered past includes a wife who is in the process of divorcing him partially because of his near-total irresponsibility as well as several brushes with the law as he spent years developing and using his considerable con-artist skills.

In “Thirteen,” Eddie is sort of roped into defending a young movie star who is accused of murdering his wife and his friend when he came home to find them together in bed. The prosecution has incredibly convincing evidence — DNA, fingerprints, perpetrator opportunity, motive. Open and closed. But Eddie senses that the kid’s claim of innocence is sincere. The problem, of course, is that sensing innocence is not the same as proving it. So the investigation begins.

All of which brings us to the single most unique and fascinating element of the novel: the villain. And this villain, Joshua Kane, is even more of a significant presence in the novel than the putative hero. What a character; what a guy! Brilliant, amoral, cunning, sick, a man with a mission — a mission that has boiled down, ultimately, to murdering as many people as humanly possible — without ever getting caught. Worst of all, there is method to his madness. The method involves being on the very jury that is trying each case; thus the novel’s subtitle: “The serial killer isn’t on trial. He’s on the jury.”

Any more information would be a certain spoiler. But herewith, just one more important point: Unlike most other procedurals, this one tells us immediately who the villain is. Then again…well…that information is not nearly sufficient to solve the cases. To name the villain is not to find the villain. Nor is it enough to diminish the suspense. Enjoy!

Review by Jack Kramer.

Please note: This review is based on the final, hardcover book provided by Flatiron Books, the publisher, for review purposes.