While Sam investigates the murder of an Iranian exile working to overthrow the current regime, he must also try to save Agent Rountree, a new agent who’s having an unexpectedly adventurous first day on the job, when he accidentally triggers a bomb. Also, Nell makes a decision about her future with NCIS.
Callen and Sam work with Navy Capt. Harmon Rabb, Jr. to apprehend spies aboard the USS Allegiance. Also, Hetty partners with Marine Lt. Col. Sarah “Mac” Mackenzie to neutralize a missile attack in the Middle East, and Kensi and Deeks are trapped in a mobile CIA unit in Iraq while under attack by ISIS.