I started reading the Mary Russell and Sherlock Holmes series back in 1994 when I chose 3 books from the library that all had the word 'bee' in them. I didn't realize that coincidence until arrived home. I read two of the books and then picked up The Beekeeper's Apprentice and realized it dealt with Sherlock Holmes and his apprentice, Mary Russell. I was not thrilled but felt a personal challenge to read all three of my 'bee' books.
I was hooked by the time I finished that first book. King's books are a little more intelligently written than the average cozy mystery and so usually more thought-provoking.
Dreaming Spies takes Russell and Holmes to Japan on a well-deserved vacation. Being the keen observers that they are they cannot miss the subtle clues to something amiss among several of the passengers on their ship. They meet a beautiful but very cunning young Japanese woman who completely capture their interests. And, as you suspect, they are drawn into a mystery and thoughts of a leisure vacation are set aside.
King is a top-notch writer and has developed a believable character in Mary Russell and her relationship with the older Sherlock Holmes. I have loved every book in this series, though I think each one is even better than the last.
* I received a copy of Dreaming Spies from NetGalley in exchange for my review. No other compensation was received.