|A Difference in Kind|
|Directed by||John Polson|
|Written by||Jason Tracey|
|Air date||May 8, 2016|
|Previous||"The Invisible Hand"|
A Difference in Kind is the 24th episode and finale of season four. The episode was directed by John Polson. It premiered on May 8, 2016.
At the end of The Invisible Hand Sherlock and Joan discovered an explosive device in the brownstone. Sherlock is able to disarm the bomb. The person who planted the device was seen by Morland's head of security and subsequently shot and killed.
Sherlock and Joan come to the conclusion that the intention of the bomb wasn't solely to kill them, but to destroy Joshua Vikner. Vikner would have been blamed for there deaths and then killed, because the one rule left by Jamie Moriarty was that Sherlock and Joan were not to be touched.
A meeting is arranged with a woman, Zoya Hashemi, she is a commander within Moriarty's former organization. She reveals that after Moriarty's capture some members wanted a new leader form outside the group, and their first choice was Morland Holmes. This was the reason for the assignation attempt on Morland's life, Vikner was trying to eliminate the competition.
Morland's arranges a meeting with Vikner, Vikner believes it is for Morland's surrender and death, but with Zoya’s men at Morland's side, the group turns on Vikner and kills him, leaving the body for the NYPD, as well as Joan and Sherlock, to find. Morland becomes the new head of Moriarty's crime syndicate, but he tells Sherlock he plans to dismantle it from the inside.