I've been following John Dunning's mystery series about cop-turned-bookseller Cliff Janeway for a number of years. This one, which came out in 2006, looks as if it will be the last; his website says problems originating from a "large benign brain tumor" have prevented further books. Here's hoping he's having a good life otherwise.
Cliff has been called up to a remote ranch to evaluate the book collection of the late horse trainer H. R. Geiger. (Not to be confused with the disturbing artist H. R. Giger.) What Cliff finds is the remnants of an extremely dysfunctional family (and family business), with surviving offspring and employees squabbling over the estate, now in legal limbo.
The title's "bookwoman" is Candice, Geiger's lovely young wife who predeceased him by several years. When Janeway gets a chance to examine her collection, he discovers that a number of rare and valuable volumes have been snitched and replaced with crap. And (eventually) it develops that he's expected to determine whether Candice's death was due to foul play.
Janeway needs to untangle a Ross McDonald-like tangle of bad behavior going back decades. He goes undercover, doing horse-work with a trainer in order to plumb memories of Candice, H. R., and their relatives and associates. It all works out to an untidy conclusion.
I have to say: it was a long read, over 500 paperback pages. Could have easily trimmed 150-200 of them without loss to plot, character, or setting. But it's clear that Dunning loves the world of horse-racing just as much as his normal rare-book world. It's funny: there's more discussion of horse stuff here than there is in the typical Dick Francis novel, and Francis was supposed to be the horse guy.