Under Secretary of Defense Corbin Duggan takes over the NCIS Los Angeles unit when they fail to find a mole.
The team travels to Syria to capture a High Value Target, but someone gets hurt when the mission goes awry.
The NCIS LA team investigates an abduction case while down two members, with Hetty being held in D.C. for questioning, and another still in the ICU following the mission in Syria.
After a Homeland Security agent is poisoned by a notorious Triad assassin, NCIS uncovers a warehouse of counterfeit purses and a money trail to stolen government funds. Also, Nell joins the team in the field.
The hug of a navy machinist with high security clearance sends the team on a city-wide hunt tracking evidence. Also, Anna Kolcheck partners with Callen, and Sam assists Hetty in the on-going mole investigation.
After a maintenance man saved the life of a lieutenant commander, the NCIS team uncovers his dark past which puts a local teenager in danger. Also, Sam must decide which colleague to take to the Los Angeles football game.
Callen goes undercover as a patient in a mental health hospital to search for an NSA agent who disappeared while tracking an ISIS cell trying to cross the Mexican border.
After a graduate student developing an electromagnetic weapon for the Navy is attacked, the NCIS team discovers a connection to international warfare. Also, Kensi continues grueling physical therapy for her spinal injury.
After Callen's father, Garrison is found in an NCIS patient's hospital room during a radiation poisoning case, Callen must take him to the boatshed for interrogation. Also, the team discusses their Thanksgiving plans.
After an unknown female assailant kills two men disguised as Sherriff's deputies in front of Callen's home, the NCIS team gets a new lead in the ongoing mole investigation. Also, Nell visits a prison to interview an inmate withholding information on the department's leak.
Sam partners with Anna and Callen with Deeks as the team investigates the disappearance of a Navy Lieutenant Commander who is working with the NSA on foreign cyber threats. Also, the team celebrates the holidays together.
After a Navy reservist is killed while protecting a city councilman, Sam is sent undercover in a private security firm with links to several criminal organizations. Also, Callen and Anna discuss the next steps in their relationship.
The mole has once again compromised the NCIS team as planted evidence results in the arrests of Callen, Sam, Granger and Deeks, on the day Under Secretary Duggan returns for Hetty's resignation.
Hetty goes rogue, leaving the NCIS team completely in the dark, and the mole kidnaps one of the agents.
Emotions run high for the team as one agent is held in an unknown location and tortured by the mole, while another discovers he was betrayed by someone he least expected.
After a retirement home resident is kidnapped, the NCIS team uncovers a pair of con artists: Ginger and Edward O'Boyle, who hop from home to home scamming the elderly out of their money. Also, Callen confronts his father on his illegal activity and the danger it places on their family.
Sam assumes a former alias in a risky undercover operation to take down an elusive drug lord. Also, Hetty interrupts Callen and Anna's romantic night to assign them a prisoner escort mission.
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 Flynnarrives from the NCIS Cyber Office in San Diego to run Ops while Eric and Nell are on assignment.
After an engineer who was developing a new guided missile destroyer is cuddled, Callen and Sam go undercover to track his co-worker aboard a plane to Tokyo to sell the classified intel. Also, Deeks plans a surprise get-together for Kensi and her out-of-town friends..
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 a highly decorated Navy Captain, Charles Langston, kidnaps a Veterans Affairs administrator who has been siphoning funds, the NCIS team must work with Hetty's former Vietnam War colleagues, now-retired Admiral AJ Chegwidden and Admiral Sterling Bridges to solve the case.
A gold heist investigation has the NCIS team working with Hetty's former Vietnam War colleagues, Retired Admiral AJ Chegwidden, Admiral Sterling Bridges and Retired Captain Charles Langston.
After Sam's wife, Michelle, is taken from her home, the kidnappers demand the prison release of Tahir Khaled, Sam's arch nemesis, in exchange for information on her whereabouts.
Following the kidnapping of Sam's wife, Michelle Hanna, Sam goes rogue from the NCIS team and attempts to stop his arch nemesis Tahir Khaled from ever targeting his family again.