'NCIS' Season 18 Finale: Is Emily Wickersham Leaving As Ellie Bishop? On 5/26/21 at 6:38 AM EDT NCIS viewers this season have had to cope with losing Jack Sloane (played by Maria Bello) this season, and have been following the rumors that Mark Harmon is set to reduce his time playing Gibbs on the show. With fans of the CBS show focusing on Sloane and Gibbs, they were completely blindsided by the Season 18 finale that seemed to show Ellie Bishop (Emily Wickersham) blowing up her job in the team in order to go undercover. In Season 18, Episode 16, titled "Rule 91," Bishop is revealed to have leaked a confidential National Security Agency (NSA) file a decade ago. She would have never been found out had that file not turned up during the hunt for two arms dealers.