Despite his grim discovery, Tulkinghorn remains undeterred from his ruthless inquiry into Lady Dedlock's past. A young crossing sweeper, Jo, mayhold a key to the mystery. Krook discovers evidence in Nemo's room which could provide a crucial clue. Richard and Ada plan their engagement, but receive an unexpected setback. And as Richard begins a career in medicine, Esther meets an attractive young doctor called Allan Woodcourt.

A chance encounter in the country raises intriguing questions for Esther and Lady Dedlock. Legal clerk Guppy, still besotted with Esther, discovers surprising new information about her past and decides to dig deeper still. And Lady Dedlock's secret is far from safe, as Tulkinghorn stumbles across a lead which could destroy her reputation forever.