It's 1925, and Mary Russell recounts an adventure only hinted at earlier--the three weeks she and Holmes spent in Japan, between India (The Game) and San Francisco (Locked Rooms), along with the journey from India to Japan on the cruise ship Thomas Carlyle. On board the ship, they meet the Darleys--the Earl, whom Holmes believes to be a blackmailer, his new wife, and his adult son, as well as Miss Haruki Sato, a young Japanese woman headed home after studying in America for a year. There's definitely something unusual about Miss Sato, but Holmes, Russell, and quite a few of their fellow passengers are happy to take lessons in Japanese language and customs from her, both the while away their voyage and to prepare for their time in exotic Japan.
It turns out Miss Sato has a particular reason for wanting Holmes and Russell in particular well prepared. They're being prepared for a particularly important client.
This is both an exciting case, with danger and adventure in both Japan and England, and a fascinating look at Japan in the years after World War I, with World War II not yet visible on the horizon. Russell's is a good narrative voice, and both she and Holmes are strong, engaging characters.
I received a free electronic galley of this book from the publisher via NetGalley.