A workmanlike mystery thriller that sets up a couple of intriguing situations but the solution for both turns out to be somewhat lacking in thrills. Ironically the two plots show off different aspects of thrillers, with one coming across as an antique approach and the other more modern.
The A plot, involving the series hero who has no name, aka "The Nameless Detective," is the more gimmicky of the two and the one that resembles a Golden Age detective yarn. The detective is hired by a guy he doesn't like to solve a locked-room puzzle. Valuable old books have been stolen from a locked library. The gimmick: the books are all first edition mysteries -- Dashiell Hammett's "The Maltese Falcon," for instance. Turns out the library belongs to a rich old guy who loves classic mysteries and collects them. (I kept waiting for someone to mention the king of the locked-room mystery, John Dickson Carr, but no one did.) Before the ND can solve this mystery, a murder is committed inside that same locked room, and now he's got to figure out if the two are connected. The solution to the book theft is pretty sweet, but the solution for the murder seems just a tad TOO gimmicky.
The B plot is the one that's more like a modern detective story. Someone is harassing two brothers who as far as they know have no enemies. They're baffled about who would pour acid on their father's headstone at the cemetery, destroy construction equipment at a job site and burgle a garage, beating one brother with a tire iron. An operative for the ND's agency, Jake Runyan, applies some shoe leather to the question and quickly figures out what the readers will have spotted right away, namely that this has something to do not with the brothers but with their dead father. After that the detective never makes a single wrong move and all his hunches pay off, which robs the plot of any real suspense. It's about as thrilling as watching an old episode of "Cannon" or "Barnaby Jones."
All in all, a diverting book but not a satisfying one. But if you write 23 mysteries starring the same character or two, at least some are bound to be clunkers, I guess.