When a Navy Admiral's daughter is the prime suspect in a double murder case aboard a research boat, the NCIS team partners with the Coast Guard Investigative Service to work the case. Meanwhile, Lasalle tracks down his estranged brother.

After an NCIS agent is killed during a security detail for the Vice Chief of Naval Operations, the team must determine if this was an assassination attempt or if someone is targeting one of their own. Meanwhile, Agent Brody is placed under investigation and her mysterious past is reevaluated.