This novel has Mary Russell and her husband, Sherlock Holmes, visiting Morocco. Russell awakes alone in a room that she doesn't remember ever seeing with wounds as if after a fight and blood on her hands. She has no idea who she is or how she got here. When she sees soldiers heading for the house where she is, she escapes through a window and wanders the town, trying to clear her head enough to remember who she is and what she was doing.

As the shadows slowly part, she and Holmes are reunited at the home of the French General who oversees the forces in Morocco. France and Spain both have parts of Morocco and there are also native troops who are fighting to regain ownership of their country. The French General is a cousin of Holmes and is in favor of the native army but wants any changes to be done slowly and under supervision. The natives, led by a military genius, want instant change. Both men are under threat of assassination. As the plots and subplots unfold, Holmes and Russell are separated again and both end up in an old dungeon, chained to the wall in the dark. Their friend who is also there is about to die as the captors are not providing food or water. Can the pair gain their freedom and help the situation in Morocco?

This is the twelfth novel in the Mary Russell series. The relationship between Mary and Holmes is fascinating. Mary is an independent woman whose skills make her a true partner to Holmes. This one has many political plots and subplots along with a charming new character, a mute boy who helps both the characters more than once. This book is recommended for mystery readers.