Holmes and Watson's new careers as consultants for Scotland Yard in London take them inside the tabloid journalism industry when a popular model is the victim of an acid attack. Also, at Watson grows increasingly homesick for New York, Captain Gregson is wracked with guilt over his unresolved rift with his former consultants.
Holmes and Watson try to work a stateside investigation from London when someone close to them (Captain Gregson) is gravely wounded by an unknown perpetrator in the United States. However, Holmes' stateside legal trouble - the result of a confession to a murder he didn't commit - threatens to derail their efforts.
Holmes attempts to secure his legal re-entry to the United States by leaning on his father's crooked relationship with the FBI. Meanwhile, Watson is enlisted by Bell to help investigate a murder for a storage facility used by wealthy clients to avoid customs and prying eyes.
An explosion caused by a crash at a road intersection leads Holmes and Watson to try to determine who manipulated traffic lights to cause the crash, and why. Also, as Captain Gregson begins his road to recovery, he, Holmes and Watson suspect that there's a larger game at play.
When a jogger is fatally stabbed during a race and a double homicide is found shortly thereafter, Holmes and Watson try to find the link between the seemingly unconnected murders and unravel the perpetrator's full scheme. Meanwhile, tech billionaire Odin Reichenbach hires the duo to investigate a personal threat he believes originated from within his own company.
Tech Billionaire Odin Reichenbach asks Holmes and Watson to assist him with the development of a program he created to predict future crimes. Also, Detective Bell enlists the duo to help locate an NYPD officer planning a sniper shooting.
Holmes and Watson investigate the murder of a criminal who made his living by stealing from other criminals. Also, when Captain Gregson resumes leadership of the precinct, he suspects his interim replacement, Captain Dwyer, is responsible for one of his best detective's suspicious departure.
Holmes and Watson work to determine if a long dormant serial killer has resurfaced in the wake of a sculptor's murder in New York City. Also, Watson suspects Holmes is keeping something from her regarding tech billionaire Odin Reichenbach.
Holmes and Watson's foe, Odin Reichenbach, asks them to test his new crime prevention system; tasked with investigating someone the program predicts will commit a crime, they worry Odin will take drastic action.
Following the murder of Morland Holmes, tech billionaire Odin Reichenbach inadvertently provides Holmes and Watson with a lead that could give them evidence that brings him to justice. But when all their options run dry, Sherlock decides to take very drastic actions.
Three years after Reichenbach’s arrest, Sherlock is lured back to New York when an associate of Jamie Moriarty tells Joan that she is dead. Sherlock is offered a position with the NSA under McNally, but he turns it down when he learns that Joan has breast cancer. A year later, Holmes is at Moriarty’s grave when McNally approaches him again with his offer, but Sherlock declines, and he and Watson go to the 11th to offer their services as consulting detectives to Captain Bell once Watson is cancer free.