While investigating an explosion that kills two people, Sherlock discovers a crime that’s been lying dormant for years. Meanwhile, Watson encourages Sherlock to finally pick a sponsor.

Joan investigates her first solo case when a wife disappears. The missing woman left behind a tear-filled video that mentions a murder on a subway platform. While Joan searches for the vanished lady, Sherlock probes the murder.

Sherlock and Joan hunt for the accomplice of a murdered blackmailer who targeted families of rape victims. Meanwhile, Sherlock resists celebrating his first year of sobriety.

When a hedge fund manager who was also running a Ponzi scheme is murdered, Holmes and Watson must determine which of his clients is guilty. Also, Sherlock contemplates sponsoring a fellow recovering addict.

When Watson joins forces with Holmes and Kitty to locate a missing nurse she used to work with, the woman’s trail leads them to another person who has recently disappeared.

When 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. Also, Holmes learns important information about his recovery sponsor, Alfredo, that strains their relationship.

Holmes and Watson take on an investigation of a personal nature when Holmes’ recovery sponsor, Alfredo, suddenly disappears. As they delve into Alfredo’s life for clues, Holmes questions whether their friend has been abducted, or worse, if he suffered a relapse into addiction.

When an archeologist is murdered, Holmes and Watson believe the man may have been killed for what he discovered during his last excavation in a local landfill. Also, Sherlock’s relationship with Alfredo, his friend and former sobriety sponsor, hits a rough patch.

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.