Original air date: 10/01/2017 Runtime: 42:24 min. After Hetty turns in retirement papers and then disappears, Executive Assistant Director Shay Mosley (Nia Long) arrives in Los Angeles to oversee the team and immediately makes staffing changes. Also, still mourning the death of his wife and living in a trailer on the beach, Sam is adamant that Callen find a new partner.
Original air date: 10/29/2017 Runtime: 43:07 min. Sam goes undercover as a day trader after a prominent investment banker with ties to a Russian oligarch is murdered. Also, one of Callen's aliases is the victim of credit card theft, and Mosley is concerned it signals something bigger.
Original air date: 11/19/2017 Runtime: 42:45 min. The NCIS team must locate a group of unknown assailants who illegally crossed the border and attacked California Highway Patrol officers. Also, Homeland Security sends over Specialist Sydney Jones (Ashley Spiller), Nell's older and bossy sister, to assist NCIS with the case.
Original air date: 12/17/2017 Runtime: 42:29 min. The team investigates a ransomware attack that takes out the entire power grid for west L.A. and paralyzes the city. Also, as the first holiday season since the death of Sam's wife approaches, he struggles to find the best way for his family to celebrate.
Original air date: 03/11/2018 Runtime: 43:07 min. Callen, Sam, Kensi and Deeks join Hetty's team from the Vietnam War, Sterling Bridges (James Remar), A.J. Chegwidden (John M. Jackson) and Charles Langston (Carl Lumbly), in a dangerous and off-the-books rescue mission to save Hetty from her captors in Vietnam. Also, Mosley calls in Nell's sister, homeland security specialist Sydney Jones (Ashley Spillers), to assist the team in Los Angeles with processing evidence connected to Hetty's time in Vietnam.
Original air date: 03/25/2018 Runtime: 42:06 min. Callen pursues every alternative when the Diplomatic Security Service apprehends his father, Nikita Aleksandr Reznikov (Daniel J. Travanti), as part of an exchange for two American photographers being held hostage in Iran. Daniel J. Travanti guest stars as Nikita Aleksandr Reznikov, Callen's father.
Original air date: 04/08/2018 Runtime: 43:05 min. Callen and Sam join forces with Anna Kolcheck (Bar Paly) and the Bureau of Alcohol, Tobacco and Firearms (ATF), when Arkady Kolcheck (Vyto Ruginis) warns NCIS that a notorious international weapons dealer has returned to the states.