I've never actually read a Conan Doyle novel or Sherlock Holmes with the exception of a simplified version of the Baskerville Hound (you know how they take classics, and then reduce them to their plot points so young children can feel like they're reading classics? That was my experience with Holmes, except it was in 6th grade and we read it in my English class at my German school so it was for second year English students). It's actually weird because I loved mysteries when I was younger but I focused more on Agatha Christie and her characters, Miss Marple and Hercule Poirot. Still, it's impossile not to be aware of the figure of Sherlock Holmes and Dr. Watson. I also tend to enjoy reimaginings of old novels when done well (I hated and didn't finish Ahab's Wife, but love Atwood's short story "Gertrude," a riff on Hamlet). Additionally, in the past few years, I've noticed that while I still enjoy the occasional mystery/thriller, I tend to gravitate towards ones set in the past when forensics weren't quite so developed, such as Stephanie Pintoff's or Ariana Franklin's novels. This may be because after years of mysteries and CSI-type shows, it is hard to be surprised anymore so it's nice if the novels have something else to offer besides a mystery, such as a glimpse into the past. While I at first hesitated to pick this up until I read some actual real Sherlock Holmes novels, all the other factors convinced me to get this.
Overall, I enjoyed the novel, but it is obvious that this novel was written as the first of a series, and not just because Mary Russell keeps referring to events in the future. King devotes a great deal of time to introducing the characters, setting the scene and showing the reader how Russell's relationship with Holmes developed. As a result, there are actually a few small mysteries in the beginning that illustrate their burgeoning relationship and the novel is somewhere between a third to halfway through before the novel actually delves into the main mystery. By the way, this is one case where the back of the book gave too much away - while certain connections may have been obvious to readers anyway, the cover already gave them away, thus leaving the reader waiting for Holmes and Russell to catch up.
When Mary Russell and Holmes first meet, Holmes is in his fifties (he explains that Watson aged him in his stories since readers might have had doubts if Watson had told of a younger detective) while she is fifteen, and he is pleasantly surprised by her intelligence and wit. Their relationship remains platonic throughout the novel though there are hints of possibilites, so I'm not a huge fan of the age difference, but I understand the author's choice - by having Russell be 15, it would explain why Holmes would take an interest in developing her mind, and he could still think of her in an asexual way. If she had been older, it would have been a bit more difficult to train her in the arts of being a detective. While I have not read actual Sherlock Holmes novels, I understand that Watson has a certain sense of awe for the character and his amazing skills of deduction. Russell, on the other hand, is more his equal when it comes to these abilities, so she portrays him in a different light, though still with great respect and admiration.
The first big case that Holmes and Russell work together involves a kidnapping in Wales, but life quickly goes back to normal until Holmes finds himself and those he cares about threatened by an unknown entity. I don't think the mystery itself was really that strong or interesting, and to be honest, I don't feel like it was really one of those where the reader can play along too much. However, I liked the character development, and as I said, this novel felt more like an introduction, so I am not using this one to determine whether the mysteries are well thought out and developed. I'll definitely be picking up the next one in the series before I make any final judgements or determinations.