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.
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.
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 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.
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.
LAPD Detective Whiting calls in a favor when Deeks' former partner goes rogue.
Kensi is transported to a missile launch facility to help thwart a takeover of nuclear weapons.
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.
Callen and the team question Joelle's backstory after she escapes from a kidnapping and turns to Callen for help.
The team tracks a highly-skilled assailant determined to avenge her father's death by killing a Brazilian diplomat.
The team investigates a ransomware attack that disrupts the entire power grid and paralyzes the city; Sam struggles to find a way for his family to celebrate the holidays after his wife's death.
After napalm is detected at a crime scene, the team investigates the sole casualty for possible links to terrorism.
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 joins Hetty's team from the Vietnam War in a dangerous rescue mission to save Hetty from her captors in Vietnam; Mosley calls in Nell's sister to assist the team in Los Angeles with processing evidence connected to Hetty's time in Vietnam.
Callen and Sam pull Granger's daughter, former spy Jennifer Kim, from witness protection to help the team locate a spy who has obtained an arsenal of bomb materials.
Callen pursues every alternative when his father is apprehended as part of a planned exchange for two American photographers held hostage in Iran.
While investigating a missing person's case, the team uncovers a killer who puts on shows for high-paying voyeurs; Mosley assigns Callen as her partner on a joint ATF mission to apprehend someone from her past.
A notorious international weapons dealer returns to the states; Eric must go under cover at a bank.
Sam and Hidoko are sent under cover after a cryptocurrency farm is robbed of over $10 million in bitcoin codes.
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.
The team partners with the FBI when a Marine dies after being exposed to a rare nerve gas; Deeks shares his dream to quit law enforcement and open a bar.
The team investigates the murder of a federal prison inmate who was the adopted daughter of a notorious counterfeiter; Callen is summoned by the ATF Internal Affairs board to discuss Anna Kolcheck's actions.
Sam is shot during a firefight with the cartel; an interrogated suspect reveals new information on the whereabouts of Spencer Williams, the man who kidnapped Mosley's son; the team travels to Mexico for a risky mission to rescue Mosley's son.