Elementary - Season 3, Episode 1: Soundtracks

After dismissing Sherlock, Joan reviews the hotel security tape from the lobby and after awhile she begins to notice a discrepancy within the recording; Overview of Allison March's house and estate.

Joan leaves the brownstone, outside Kitty stops her and asks her why she decided to join up with Sherlock when she had another brighter career path. Joan answers, then asks her the same question.