While Sam and Deeks recover from traumatic torture that will have a lasting impact on their personal and professional relationships, lives are still in jeopardy as the NCIS: LA team searches for stolen nuclear weapons.
In an effort to help Sam and Deeks return to work, Hetty calls upon Operational Psychologist Nate Getz to help them cope with their traumatic experience. Meanwhile, the rest of the NCIS: LA team investigates the murder of a former Navy Admiral and a controversial journalist aboard a private jet.
Analyst Nell Jones joins the NCIS: LA team in the field when a former Navy officer’s girlfriend is kidnapped in exchange for Navy intelligence. Meanwhile, Deeks unknowingly breaks one of Hetty’s rules.
Callen and Sam enlist the help of a Gurkha, an elite Nepali soldier specializing in knife fighting, to retrieve a missing thumb drive. Meanwhile, Kensi and Deeks struggle to find a balance in their partnership.
A senator’s daughter is the victim of a home invasion. The team investigate to determine if it was a random crime or a targeted attack due to her father’s crackdown on international cyber warfare. Meanwhile, Kensi’s holiday spirit changes after she receives a surprise Christmas gift.
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.
Sam is convinced that the theft of software for a new unmanned aerial vehicle is connected with the disappearance of the lead engineer's 10-year-old daughter, a girl Sam once provided protection detail for in Saudi Arabia.
When the NCIS: Los Angeles team and DEA uncover the cartel's plans to slyly transport billions of dollars’ worth of cocaine from Colombia to the U.S. using a submarine, Callen and Sam must quickly locate the missing vessel. Meanwhile, Hetty is called to Washington in the aftermath of the controversial mission in Afghanistan.