Callen and Sam travel to the USS Allegiance in the Persian Gulf to work with Navy Captain Harmon "Harm" Rabb, Jr. (David James Elliott) when the NCIS team uncovers ISIS sympathizers who are targeting military locations.

Callen and Sam work with Navy Captain Harmon "Harm" Rabb, Jr. (David James Elliott) to locate a group of ISIS sympathizers aboard the USS Allegiance. Also, Hetty enlists her friend, Lieutenant Colonel Sarah "Mac". Mackenzie (Catherine Bell), to help obtain information from a Russian diplomat.

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.