A bored Sherlock forces his investigative services onto Joan, who is trying to locate a woman who has been missing for five years, and the only clue is the smell of nutmeg at the site of her disappearance. Meanwhile, Joan’s bond with her long-distance boyfriend, Andrew, is tested when a man from her past reappears and asks for her help.

When Holmes is implicated in the murder of a woman who was killed during the height of his addiction, he investigates himself to find their connection. As Holmes retraces his steps with Watson’s help, the clues make his confidence in his own character waver.

Holmes and Watson investigate the murder of a professional skeptic, a man who debunked paranormal, religious and scientific phenomenon for a living. The case becomes urgent when his homicide reveals a potential threat to homeland security. Also, Captain Gregson’s daughter and fellow NYPD officer, Hannah, asks Watson for help with one of her cases.