The NCIS LA team investigates an abduction case while down two members, with Hetty being held in D.C. for questioning, and another still in the ICU following the mission in Syria.

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.