Blackmailed and sidelined from investigating, Sherlock Holmes finds hope when a young woman arrives on his doorstep, potentially holding the key to solving the kidnapping of an ambassador's daughter.

Amelia goes under cover to search for clues at Clara's home; Sherlock goes to prison under pretense of meeting his forever foe, Moriarty.

Amelia withholds details from Holmes after encountering a charming man with a pistol, but Sherlock must step in when her investigation turns fatal.