Hetty is being tortured by her captors in Vietnam; Eric and Nell find a clue to her whereabouts; the team organizes a rescue mission.
NCIS: Los Angeles episode guide
After napalm is detected at a crime scene, the team investigates the sole casualty for possible links to terrorism.
Callen and the team question Joelle's backstory after she escapes from a kidnapping and turns to Callen for help.
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.
Kensi is transported to a missile launch facility to help thwart a takeover of nuclear weapons.
LAPD Detective Whiting calls in a favor when Deeks' former partner goes rogue.
Sam goes under cover as a day trader after an investment banker who has ties to Russia is murdered; one of Callen's aliases is the victim of credit card theft.
When weapons worth $1 million are stolen, the team tracks the evidence to a charity event; Mosley gets herself added to the event's guest list, bringing Callen and Sam along as her security detail.
During the murder investigation of a Navy Lieutenant on leave in Los Angeles, the team uncovers classified surveillance briefs she smuggled into the city that may have been sold to a foreign buyer.
When the daughter of a notorious counterfeiter arrives in Los Angeles, Sam goes under cover as a financier; Callen partners with Anna to track the family's latest scheme.
When Hetty turns in retirement papers and disappears, Shay Mosley comes to Los Angeles to oversee the team and makes staffing changes; Sam insists that Callen find a new partner.