A deceased Marine is found encased in a Civil-War era tomb at the Smithsonian museum. Ziva David joins NCIS as a liaison officer for Mossad and is assigned by the new director of NCIS to Gibbs's team without his consent. She is forced to prove her worth to the team as they track down the people responsible for the officer's death, which is linked to a Civil War treasure. When Ducky and Ziva are placed in a difficult position, Ziva shows her value by saving both their lives.