Holmes' former sobriety sponsor, Alfredo, asks for his help with an illegal endeavor in order to save his brother. Also, Holmes and Watson investigate the poisoning of a biology professor who was working on a secret genetics project prior to being killed.

Holmes engages an old foe to protect his father after he learns Morland 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.