As the search for stolen nuclear weapons is revived, Hetty sends Callen and Kensi overseas while Deeks helps stateside as Sam and Michelle go undercover.
Looking for information on a notorious arms dealer, Deeks goes undercover and makes friends with a female source. While keeping surveillance on Deeks and the woman, Kensi is challenged by new emotions.
The missing body of a cartel boss sends Kensi and Deeks to Mexico while the rest of the NCIS team looks for a potential leak within the DEA's special task force.
After a Navy lieutenant and pilot are poisoned by cyanide laced water, the NCIS team investigates to see if the two were targeted or if it was a trial run for a large-scale contamination.
When a murder weapon in Idaho matches a case in Los Angeles, Callen and Sam head to Idaho to join NCIS: Red, a mobile team who travel to various locations to solve crimes.
Sam fears for his family's safety when his wife is called to resume a former CIA cover after a case suggests ties to the infamous Sidorov and his stolen nukes. Aunjanue Ellis guest stars.
A Marine's death raises suspicions from his wife about his last battle. Sam and Callen try to find out whether there has been a cover up. When Hetty invites Operational Psychologist Nate Getz, the team suspects an evaluation is coming up.
The NCIS team investigates an international car shipping ring when a woman from Deek's past is found to be involved. Kensi goes undercover at an auto body shop as part of the investigation.
The team is spread out for the holidays with Callen, Sam, Kensi and Deeks at sea looking into the death of an NCIS agent. While Hetty decides to take a trip, Eric and Nell keep thingsgoing back at headquarters.
When a crime is posted on the internet, the NCIS team heads to the beach to investigate any links a surfer and a dead Naval tech scientist might have to the video.
After recieving a cryptic voice mail from a former CIA colleague, Sam Hanna is taken to a warehouse where he encounters a dead body, a large white poodle, layers of paper work and books, and a mystery that takes the OPS team down a rabbit hole of dog shows and covert spies.
It's an issue of national security as the NCIS team investigates whether the death of a U.S. senatorial candidate's staffer was an accident or a murder.
When four people are killed in an explosion at a diner, NCIS is brought into to investigate as they were linked to a classified project. Kensi finds herself sympathizing with a teenager that is related to the investigation.
Following a drone strike in Afghanistan and the finding of a retired marine's body in the ruins of the bomb-making compound, the team investigates the man's loyalties and connections to the Taliban.