Mary Russell and Sherlock Holmes are caught up in a case that turns intensely personal, shining light on a past that even Holmes himself did not suspect.
After their recent adventures in Transylvania, Mary Russell and Sherlock Holmes look forward to spending some time getting to know Holmes' son, the artist Damian Adler, and his family. But when they arrive at Damian's house, in a small village south of Paris, they discover that the Adlers have fled from a mysterious threat.
Holmes takes off in pursuit, leaving Russell, who has been slowed down by a recent mishap, to explore the empty house. In Damian's studio, she discovers some newly-arrived crates that are packed with sketch-books, letters, and memorabilia somehow linked to an earlier generation of French artists, Holmes' grand-uncle, Horace Vernet. It's an odd mix of treasures and clutter, including a velvet-lined box holding a tarnished silver lamp with a rotating shade and dozens of strips of paper. On each strip is a sequence of fifteen progressing figures, which dance into motion when the shade is spun: an antique, charming, yet highly sophisticated form of zoetrope.
Deeper down in the same crate is what Russell suspects to be an old journal, although it is written in a nearly impenetrable code language. Intrigued, and trying hard to ignore her anxiety about Holmes, she sets about deciphering the intricate cryptograph. There appear to be fifteen entries. Each, she slowly discovers, is built around an image. The first? A child, bundled into a carriage by her abductor, watches her weeping yet unprotesting mother recede from view.
The decoding is slow, painstaking work, and each revelation leaves Russell with more questions than it answers. Who is this young woman who moved from France to India and then all over the world? What does she have to do with Damian Adler, and the threat that came first to his village, then into the house itself?
The secrets of the past are clearly reaching into the present. And it is increasingly urgent that Russell figures out how the journal and lantern are related to Damian-and possibly to Holmes himself.
Could there be things about his own history that even the master detective has not yet perceived?
