Sherlock and John, searching for the true criminal who killed Count Drebber, set a trap for the criminal using the wedding ring they found at the murder scene. Sherlock is able to deduce who the real killer is, who offers Sherlock a strange deal.

Following William’s plan, Albert invites Irene to a masquerade, where a game with the famed “Lord of Crime” as its theme is being played. Dressed as a man, Irene uses the game to contact Albert, pleading for her safety in return for the stolen papers.

John introduces Sherlock to Mary, his fiancée. A stunned Sherlock realizes that Mary has another concern. She produces six pearls, detailing their connection to her missing father. She asks Sherlock to look into the matter, but is holding something back.