Irene Adler is introduced as well and alive. She struggles with some emotional damage from her captor and Sherlock knows that he owes it to Irene to stay be her side. As Watson dives into the case she finds who was keeping Irene captive while Sherlock plans to leave New York with Irene. After thinking Irene is working with Moriarty he returns to work on the case. A man shows up in Sherlock's apartment to kill him when he is shot by Irene who reveals herself to be Moriarty.
In the second half of the episode, Moriarty AKA Irene Adler, reveals to Sherlock that she is fascinated with him and that he is game that she will always win. Sherlock eventually tracks down and solves Moriarty's big move in New York but doesn't stop her. During this time Moriarty takes Joan to lunch to convince her to back off of Sherlock where Joan figures her out. In the end Joan gets Sherlock to convince Moriarty she has won and the police take Irene into custody.