When the daughter of a notorious counterfeiter arrives in Los Angeles, Sam is sent undercover as a financier, while Callen partners with Anna to track the family's latest scheme.

LAPD Detective Whiting calls in a favor when Deeks' former partner goes rogue.

The team must find assailants who illegally crossed the border and attacked California Highway Patrol officers; Homeland Security sends Nell's older and bossy sister to assist with the case.

While Hetty is being tortured by her captors in Vietnam, Eric and Nell find a clue to her whereabouts, prompting the team to organize a rescue mission with very little information.

Callen, Sam, Kensi and Deeks join Hetty’s team from the Vietnam War, Sterling Bridges, A.J. Chegwidden and Charles Langston, 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, to assist the team in Los Angeles with processing evidence connected to Hetty’s time in Vietnam.

Callen, Sam and Nell must find pieces of a failed rocket launch, including a top-secret government device; Hetty tries to help Keane acclimate to life in the states.

Gravely injured and unable to communicate with the team in the U.S., Callen, Sam and Kensi, with an unconscious Deeks in tow, search for a safe way home as a cartel boss places a “dead or alive” bounty on their heads. Also, Mosely and retired Navy Admiral Hollace Kilbride beseech their contacts in Mexico and D.C. for assistance with their missing colleagues

The NCIS team is in danger after their pictures, as well as Mosley and her son’s names, are included on a cartel hit list. Also, NCIS Deputy Director Louis Ochoa arrives with Special Prosecutor John Rogers to interview Mosley about the off-the-books mission in Mexico.

When a newborn child is found abandoned on a Navy ship, Kensi and Deeks search for the mother on board before she dies of complications. Also, Nate meets with Admiral Kilbride and learns about the CIA project from the ‘70s and ‘80s involving children.