TV Line reports these spoilers about the storyline and their characters:
Manheim will play Diane, a devoted wife whose husband, the brilliant Arthur (Rubinek), is slowly losing his mind. While the POI team risks putting her in danger, they must rely on Diane to break through to her husband in order to save both their lives.
Their arc is set to start in early 2014.
Person of Interest airs on Tuesdays at 10 pm on CBS.