Business becomes personal for Sherlock when he is forced to partner with his estranged brother, Mycroft, to solve a case with life-or-death consequences.

Sherlock helps a math genius from his network of 'Irregulars' experts after he stumbles upon a body while participating in a math puzzle competition. Joan attempts to extend an olive branch after she learns about Kitty’s past.

Holmes and Watson join forces with the NYPD after a police officer is murdered. Also, Sherlock searches for the creator of a “recovery blog” who is posting personal statements he has made in sobriety meetings.

Holmes and Watson find themselves in the middle of a civil war being fought on the Internet when a member of Everyone, the anonymous hacker group they periodically work with, is murdered.

When Holmes and Watson investigate the murder of a fertility lab technician, they discover the woman had a secret personal life that leads them to multiple suspects. Also, the tables are turned on Watson when she’s investigated by an NYPD detective.

Holmes and Watson search for a computer hacker responsible for three murders, including the death of a Russian billionaire who was visiting New York City. Also, Joan is surprised to receive a solo dinner invitation from Sherlock’s father.

Sherlock and Joan search for a murderer who used poisonous mushrooms to kill a botany professor and a group of the instructor’s students. Also, when Joan is disturbed by loud noise next door, she discovers her neighbor, Trent, is renting out his home through a vacation site that caters to hard partiers.

At the urging of Morland’s wealthy associate, Henry Baskerville, Holmes and Watson look into the death of his brother and discover that a witness saw the man chased to his death by a large, glowing animal.

When the leader of a local street gang abducts Holmes to compel him to find the person responsible for a hit on his men, Holmes and Watson get caught in the middle of an international hunt to recover a centuries old, priceless artifact. Also, Watson debates whether a personal favor Shinwell asks of her is outside her comfort zone.

Holmes and Watson investigate the murder of a former professional eSports video game player who died after being assaulted in front of his fans during a live video stream. Also, Shinwell approaches Joan for advice when his teenage daughter asks to meet with him for the first time in years.

When a reality show contestant is murdered, Holmes and Watson zero in on another competitor as a suspect, a former war criminal who may be the most skilled killer they’ve ever pursued. Also, for the first time since he attacked Sherlock, Shinwell reaches out to Joan to ask for a favor

Watson and her half sister, Lin, have conflicting reactions when their estranged biological father dies. Also, Holmes and Watson find themselves on the hunt for a stolen plutonium shipment they fear will be used to make a dirty bomb after a department of energy inspector is killed with a lightning gun.

Sherlock and his father, Morland Holmes, attempt to repair their strained relationship upon learning of a death within their family. Also, Holmes and Watson discover a link between their latest case and the world of Egyptian antiquities when they search for a killer who tried to mummify his victim.

Detective Bell considers leaving the NYPD when he is recommended for a once-in-a-lifetime career opportunity. Also, Holmes and Watson are hired by a private client to investigate the disappearance of a young woman who led a double life online as a financial dominatrix.

Holmes and Watson receive a shocking request to collaborate from their foe, Odin Reichenbach, when the tech billionaire asks them to test his new crime prevention system. Tasked with investigating someone the program predicts will soon commit a crime, the duo worries Odin will take drastic action before they conclude their inquiry.