After a diplomatic service van transporting an unknown package from the State Department is hijacked, the NCIS team must determine who committed the crime and what has gone missing. Meanwhile, Callen and Sam celebrate five years as partners, but face one of their biggest challenges when they go undercover for a case.
The NCIS: LA team investigate a compromised intel operation after four people connected to the classified project are killed at a diner explosion. As Deeks and Kensi are on the trail of those involved, they learn that a wayward teenage girl might be related and Kensi can’t help but be empathetic to her situation.
The NCIS: LA team investigates the tragic death of a U.S. senatorial candidate’s staffer who is run over crossing the street. The high-profile case becomes a matter of national security as the agents must determine whether it is an isolated tragic incident or a politically connected plot that might put others in danger.
When a CIA agent who worked with Sam Hanna over eight years ago seeks his help and is soon found dead of an apparent suicide, Hanna and Callen suspect foul play and a bigger conspiracy. Deeks finds his inner 'dog whisperer' with Kensi as the two go undercover and enter a dog show with a prized poodle.
A former defendant of Deeks is targeted for discovering information that could dismantle a lucrative car shipping operation with links to a global terrorist ring. Meanwhile, the NCIS: LA team tackles the large-scale stolen car operation from the inside when Kensi goes undercover in an auto body shop.
A distraught widow is suspicious of the circumstances surrounding her Marine husband’s last battle and Sam and Callen help to determine if there has been a cover-up. Meanwhile, Hetty summons Operational Psychologist Nate Getz to be her “pawn” and the rest of the NCIS: LA sense another evaluation on the horizon.
Following an explosion at a fish market, the NCIS: LA team partners with an undercover DEA agent to determine if the incident is an act of terrorism or a botched drug smuggling deal. Meanwhile, in Afghanistan, Granger and Kensi investigate a helicopter crash that could be tied to their ongoing search for the infamous white ghost.
While the team investigates the death of one of three Afghanistan soldiers who are training in the U.S., they discover two other soldiers are missing and must find them before they’re forced to reveal classified military operations to their captors. Also, Sam is back to work but his team worries it may be too soon, and Callen realizes he has very little in common with his partner.
When three FBI agents are killed in an explosion following a successful undercover sting operation, the team searches for the person behind the attack. Meanwhile, Deeks and Kensi realize the team knows about their relationship, as Hetty pairs Kensi with Sam and Deeks with Callen during the investigation.
Callen and Sam resume their undercover identities as a prisoner and guard to infiltrate a white supremacy group believed to be in possession of stolen nuclear material. Kensi transforms herself into a tattooed biker chick to play the part of Callen's girlfriend. Also, Callen's first meeting with Hetty is revealed.
When a suspected North Korean spy is poisoned and hit by a truck carrying Christmas trees, the team must search for who is responsible for smuggling spies into the country. Also, Deeks and Kensi try to find a way to include their mothers in their Christmas plans, and Hetty notices that Granger isn’t feeling the holiday cheer.
After the U.S. Treasury Department is hacked, Nell and Eric go undercover inside a couple’s retreat to track a tech savvy husband and wife linked to the crime. Also, Digital Forensics Specialist Dave Flynn arrives from the NCIS Cyber Office in San Diego to run Ops while Eric and Nell are on assignment.
The NCIS team investigates a defense contractor, Rebecca Larmont, designing a nuclear attack weapon after her estranged husband, Victor Larmont, says he has proof she is selling Navy secrets to a foreign government. Also, Kensi goes undercover as a professional dancer at the Cuban club where the husband works, while Deeks is undercover as the bathroom attendant.
After Hetty turns in retirement papers and then disappears, Executive Assistant Director Shay Mosley 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.
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. Mosley calls in Nell’s sister, a homeland security, to assist the team in Los Angeles with processing evidence connected to Hetty’s time in Vietnam.
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
After the prototype for a tactical assault suit is stolen from a Navy base and used in a Beverly Hills jewelry heist, the team must determine who stole the suit and what their next target is. Also, retired Navy Admiral Hollace Kilbride temporarily oversees the team while Mosely and Hetty face repercussions for the unsanctioned Mexico mission.
Department of Justice (DOJ) Agent Lance Hamilton asks Sam for assistance in locating a former U.S. border patrol tactical officer who disappeared following a threat by the cartel. Also, Kensi and Army Criminal Investigative Department (CID) Special Agent Steve Evans partner on a dangerous mission to recover a stolen hard drive with sensitive military intelligence on it.
While Sam investigates the murder of an Iranian exile working to overthrow the current regime, he must also try to save Agent Roundtree, a new agent who’s having an unexpectedly adventurous first day on the job, when he accidentally triggers a bomb. Also, Nell makes a decision about her future with NCIS.
The NCIS team's murder investigation of a man who sold military information leads to the abduction of a doctor whose cutting edge neurotechnology could be developed into advanced weaponry. Team members are interviewed by FLETC to see if Deeks would make a good NCIS agent. Callen tries to have an important talk with Arkady.
Sam and Kilbride clash when a case involving an arms dealer responsible for the slaughter of ATF agents leads them to a well-connected General and friend of Kilbride, accused of supplying militia groups with guns. Also, Kensi and Fatima go undercover at a rehab facility to question the arms dealer's girlfriend.