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.

When William James Moriarty claims responsibility for being the Lord of Crime in all the papers, aristocratic condemnation and public anger falls upon the Moriartys. The final problem of the Moriarty Plan that William has concocted at long last begins.