Holmes's discovery of a mysterious musical score initiates a devious Christmas challenge set by Irene Adler. His preoccupation risks him neglecting the case of his new client, Danish arctic explorer Fridtjof Nansen, who has received a series of threats in the form of animal carcasses left on his doorstep. Could they really be gifts from a strange spirit pursuing him since his expedition to cross Greenland? And might this somehow be related to Irene Adler's great game?