** spoiler alert ** "A Monstrous Regiment of Women" continues Laurie King's excellent mystery series about Sherlock Holmes and Mary Russell, the young and brilliant partner he so unexpectedly acquired in "The Beekeeper's Apprentice." Mary has grown up considerably at this point, both concluding her studies at Oxford and embarking on her first independent case as a detective. Her friendship with Holmes has become subtly strained by the budding attraction between them both, so Mary decides to investigate solo when a friend comes to her for help. Her investigation leads her to a charismatic female religious leader whose wealthier followers have a habit of dying and leaving her their money. Holmes comes to lend a hand when an unknown villain attacks not only Mary's life but her sanity, and their own relationship will be tested as they struggle to close the case. I have to admit, I think the author made a mistake in bringing Mary and Holmes together in this book. Not because of the May-December aspect, which mattered not at all considering that their overwhelming attraction to one another lay in their shared intellect. But Mary and Holmes's relationship always bucked the trend by being undefinable, so to settle them down into a very definable husband-and-wife seemed a trifle anticlimactic. Still, a very good read for its very good characters.