Sherlock helps investigate a double murder that has similarities to a series of homicides that took place 13 years ago; Watson tries to learn more about the mysterious man in her care.
Nichols and Eames search for an adept killer after a woman's murder.
Mace fights for his life while Coulson and team find themselves in a deadly cat-and-mouse game as they attempt his rescue.
Detectives Lupo and Bernard tackle a complex case when four police officers are shot.