It’s only the second day of 1924, but Mary Russell and her husband, Sherlock Holmes, find themselves embroiled in intrigue. It starts with a New Year’s visit from Holmes’s brother Mycroft, who comes bearing a strange package containing the papers of an English spy named Kimball O’Hara—the same Kimball known to the world through Kipling’s famed Kim. Inexplicably, O’Hara withdrew from the “Great Game” of espionage and now he has just as inexplicably disappeared.

When Russell discovers Holmes’s own secret friendship with the spy, she knows the die is cast: she will accompany her husband to India to search for the missing operative. But Russell soon learns that in this faraway and exotic land, it’s often impossible to tell friend from foe—and that some games aren’t played for fun but for the highest stakes of all…life and death.