Callen and Sam work with Navy Capt. Harmon Rabb Jr. to apprehend spies aboard the USS Allegiance; Hetty tries to neutralize a missile attack in the Middle East; Kensi and Deeks are trapped in a mobile CIA unit in Iraq while under attack.
The murder of a Naval lieutenant leads the team investigating a potential ebola outbreak - Callen and Sam check her ship, the USS Allegiance while Kensi and Deeks follow her movements after leaving the ships.
The NCIS team reluctantly aligns with two former criminals from England, Ricky Dorsey and Frankie Bolton, after a powerful arms dealer kidnaps Ricky's daughter in an attempt to obtain a dangerous weapons system.
After a Navy lieutenant disappears from the scene of a car accident, the NCIS team processes the crime scene and discovers his laptop is missing along with recently accessed confidential information for retired Navy SEALs.