A man called Douglas has received a bullet in the head. Sherlock Holmes has deciphered a secret message warning him of Douglas's danger - too late. When he arrives at Douglas's home he finds a bizarre series of clues: the victim's branded arm, the theft of his wedding ring and a mysterious calling card. Scotland Yard is stumped, but Holmes, who has detected the evil presence of Moriarty in this crime, has some ideas of his own.