In 1866, a brilliant young orphan and his ailing younger brother are taken in by a charitable aid organization, where they catch the attention of the son of an earl, who is discontent with Britain’s class system.

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.

Receiving a new name, Bonde joins the Moriarty ranks, and is sent to retrieve the contents of a safe deposit box with Moran, Louis, and Fred. But when an unexpected bank heist spurs the others into spontaneous action, Bonde is left wondering what to do.

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.