When Watson’s stepfather writes a crime novel based on her work with Holmes without her knowledge, an underlying issue in their relationship is revealed. Also, as Holmes and Watson investigate a retired FBI agent’s murder, they discover the man’s death is connected to an unsolved case from the victim’s career.

When Watson runs into Captain Gregson and his secret girlfriend, a former NYPD officer, she inadvertently sets the couple’s breakup in motion. Also, Holmes and Watson investigate the murder of a wealthy woman who left her considerable estate solely to a beloved dog.

Holmes and Watson have plenty of suspects when they investigate the murder of a man who led a secret life as a vigilante, “catfishing” sexual predators on dating sites and publicly shaming them. Also, when Shinwell’s criminal record prevents him from finding a full-time job, Holmes disagrees with Watson’s plan to help him.

Sherlock and Joan question how well they know Shinwell when they investigate the possibility he may have gotten away with the unsolved murder of his friend, a fellow gang member. Also, Sherlock and Joan’s latest case puts them on the hunt for a treasure map rumored to lead to a fortune in pirate’s gold hidden around New York City.

Holmes and Watson retrace Holmes' steps after Holmes finds himself in possession of a severed head and can't remember anything about the last six hours.

Holmes and Watson discover that the murder of a robotics engineer may be connected to his groundbreaking secret research in the area of real-life teleportation. Also, when Detective Bell is shut out of a required class he needs in order to complete his master’s degree and join the U.S. Marshal Service, he is shocked to discover the course instructor has personal reasons for denying him access.

Holmes and Watson race to locate a missing woman when Harlan Emple, Holmes’ friend and “Irregulars” mathematics expert, becomes the prime suspect in her disappearance.