The Beekeeper's Apprentice by Laurie R. King
Picador, n.d. (originally published 1994); 346 pages
The first book in a series, The Beekeeper's Apprentice documents how Anglo-American Jewish orphan Mary Russell came to be the apprentice (and later partner) of the ostensibly retired Sherlock Holmes.
I've been a Sherlock Holmes fan for a very long time, and when I ran out of Holmes canon, I naturally moved on to Holmesiana. Of what I've read (which really isn't much), Laurie R. King has done the best job at recreating Holmes. Beekeeper's Apprentice is a great book, not just because it is about Sherlock Holmes, but because it's a good mystery with a great female protagonist as well. I highly recommend the Mary Russell series to everybody (seriously, just ask my friends, since I hound them until they read it), although the first ten are better than the later books.