Enquanto Sam e Deeks recuperam de uma tortura traumática que terá um impacto duradouro nas suas relações pessoais e profissionais, vidas ainda estão em perigo enquanto a equipa NCIS: LA procura armas nucleares roubadas.

Num esforço para ajudar Sam e Deeks a regressar ao trabalho, Hetty recorre ao psicólogo operacional Nate Getz para os ajudar a lidar com a sua experiência traumática. Enquanto isso, o resto da equipe NCIS: LA investiga o assassinato de um ex-almirante da Marinha e de um polêmico jornalista a bordo de um jato particular.

A equipe NCIS: LA deve descobrir quem comprometeu um projeto confidencial de vacina de uma empresa de biotecnologia. Enquanto isso, Deeks luta contra suas emoções ao retornar ao campo.

A equipe NCIS: LA se encontra em perigo enquanto investiga o caso de sequestro de um homem que afirma ser o pai de Callen.

A analista Nell Jones se junta à equipe NCIS: LA em campo quando a namorada de um ex-oficial da Marinha é sequestrada em troca de inteligência da Marinha. Enquanto isso, Deeks, sem saber, quebra uma das regras de Hetty.

Quando um hacker de 15 anos compromete missões, Callen se disfarça em uma prestigiosa escola secundária.

A equipe deve alertar a Segurança Interna quando descobrir uma ameaça a um trem com base em Los Angeles durante uma investigação de assassinato.

Kensi goes undercover as a nutritionist and Deeks poses as a new patient at a rehab center to investigate the death of a Navy officer.

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.

When a former Romanian Communist leader and suspected war criminal is discovered to be living in Los Angeles under a false identity, the NCIS: LA team must locate him before he disappears again.

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.

While in Afghanistan, Kensi and Granger join the team on a joint case when a federal agent in Los Angeles tied to Hawala, an ancient system of money transfer, is murdered.

The investigation into the murder of two private military contractors ends up putting a member of the team in grave danger; Sam arranges a blind date for Callen.

Callen and Sam search for a murder suspect -- a retired assassin (Danny Trejo) they encountered on their first case together.

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.

When a gang identifies and executes an undercover agent, the team must locate a mole before other agents are put in danger.

Eric witnesses his friend, a computer systems expert, being attacked by people who want information that could redirect a missile; Kensi runs into a familiar face in Afghanistan.

After learning that Special Agent Kensi Blye disappeared and the Taliban may be he holding her captive, Hetty sends the NCIS: LA team to Afghanistan on a rescue mission.

Nell joins Deeks in the field on a case involving a former Marine who is being tracked by al-Qaida after embezzling money from Iraq.

The team takes an undercover agent who is suspected of working for the smuggler he is supposed to be investigating into custody; Kensi and Deeks discuss their relationship.

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 a news reporter announces the group responsible for the deadly explosion at a military-sponsored charity event, the team must investigate her claims and search for the attacker.

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.