Complete story — includes the ending
Flashbacks reveal Sherlock's meeting with Irene two years ago and their subsequent relationship, including her "preserving" antique works of art by returning to museums her forgeries of the paintings rather than the restored originals. Irene was psychologically tortured for the past 18 months, which she believes to have been seven years. Sherlock decides to send Irene away to keep her safe, but she counters that they go together. He agrees, but then notices a mole is missing from Irene's back and concludes it was removed to avoid it turning cancerous - which Moriarty would not care about, unless she was working for Moriarty. Berating him for not trusting her, Irene storms out. One of Moriarty's agents discovers he is to be killed, but defeats his would-be assassins and tries to kill Sherlock (in defiance of Moriarty's strict orders). The agent wounds Sherlock and reveals that Moriarty is a woman. The agent is shot and killed by Irene, who now speaks with a British accent. Sherlock then realizes that she is Moriarty.
Sources and content license
Source and revision history · Adapted from Wikipedia contributors, List of Elementary episodes. HTML formatting and reference markers removed. · Content license