Season 2, Episode 15 'When Your Number's Up' - Holmes and Watson investigate a series of murders in which the killer leaves envelopes of cash on the victims. The probe leads the two into the world of wrongful death compensation. Meanwhile, Sherlock makes a generous gesture to Joan as she suffers through the aftermath of a personal crisis.
Season 2, Episode 19 'One Watson, One Holmes' - Holmes and Watson get caught in the middle of a digital war being fought on the Internet when a member of Everyone, the anonymous hacker group they periodically work with, is murdered.
Season 2, Episode 21 'Under My Skin' - Two New York City paramedics are killed during a kidnapping. Holmes and Watson join the manhunt to find the murderer and the woman he abducted. Meanwhile, Sherlock learns some important information about his recovery sponsor that strains their relationship.