- Holmes engages an old foe to protect his father after he learns Morland (John Noble) is in danger of being killed. Also, Holmes and Watson search for a killer connected to the tobacco industry when a lawyer who was in the process of reviewing a major cigarette distributor’s finances is murdered.
- John Noble guest stars as Morland Holmes, Sherlock’s father.
[(Spoiler)’s back, son]"She's back, son. And she wants what's hers. // Moriarty."