Laurie R. King skillfully blends two of her mystery series in this book. The outer plot is a possible murder being investigated by series detective Kate Martinelli of the SFPD. The dead man is a Sherlock Holmes collector and dealer, organizer of a Holmes themed dinner club, and Kate finds a manuscript he had recently acquired, which seems to have been written by Conan Doyle during his brief stay in San Francisco in the 1920's. It is, of course, "actually" (at least to those of us familiar with King's Mary Russell / Sherlock Holmes series) a manuscript written by Holmes during their stay in San Francisco detailed in "Locked Rooms", a sidestory of an investigation he undertook while Russell was away on business. King has some fun playing with us, as to whether we are supposed to believe it is a scandalous and suppressed Conan Doyle fiction, or a historical account by Holmes.
Now this kind of thing can easily blow up or become tedious, but after some initial awkwardness King pulls it off and I found myself reading each story with equal interest yet without any real frustration at having to switch off one to the other. When the Holmes story finished (it occupies most of the third quarter of the book, as Kate is reading it for clues to her own case), I'm satisfied and ready to get back to modern days. Also great fun is the balancing of Kate's skeptical introduction to the world of the Sherlockians (she had little if any acquaintance with the Conan Doyle stories, much less the mystique they have gathered) against the interior Holmes story ... for instance, the narrator of the story refers to himself as Sigerson, which Kate doesn't realize is one of Holmes's aliases (and the one under which he and Russell were travelling in "Locked Rooms").
I'd almost give this one five stars, but a few problems tilt me to four:
-- as other reviewers have pointed out, the book does drag a bit in the early middle, and when we're first plopped into the Holmesian sub-story about halfway through. But eventually, when we get used to the change, it picks up to become quite a good read and I didn't find the minor switching back and forth and eventually entirely back to the Martinelli story distracting; it even seemed to have a good logical flow.
-- another reason for the .. ahem .. drag is the occasional lengthy digressions into Kate's personal and community life, lengthy, dewey-eyed PC treatises that is. I have nothing against gay/lesbian fiction per se, and enjoy, for instance, Jane Rule's novels and Joseph Hansen's Dave Brandstetter mysteries. But these interludes seem forced, tacked on as if they, and not the story, are the real purpose of the book (which they likely are); and too picture perfect, Diversity Potemkin Villages as it were. (By contrast, the gay theme in the Holmes substory is integral to the plot and seems quite natural.)
-- although the plot builds nicely to a point near the end, where two convincing suspects are identified, the very end is unsatisfying in that Kate seems to decide, and take precipitate and drastic action, on the basis of weak evidence, and the final scenes (before another PC interlude) are less than convincing. (It doesn't help that the villain, if not the motive, was pretty obvious pretty early on.)