The third season of NCIS: Los Angeles premiered on September 20, 2011. The two hours season finale was aired on May 15, 2012 on CBS.
The Special Projects team travels to Romania to search for Hetty, while delving into the history of the Comescu crime family, and their connection to Callen. Meanwhile, Eric and Nell discover that Lauren Hunter, the Office of Special Projects' Operations Manager, is a member of the Comescus.
The NCIS team joins forces with the NSA to find the creator and controller of a software program linked to a cyber attack against the Department of Defense. Meanwhile, Callen continues searching for more information about his past.
Special Agent Sam Hanna is sent undercover as a bomb specialist as the team races to locate stolen explosives somewhere in the city. Meanwhile, to much protest, Hunter changes the dynamics of the team and has Callen partnered with Kensi and Sam with Deeks.
The NCIS team delves into the underground world of the Libyan resistance movement following the murder of a news reporter, and Hetty reveals details about Callen’s past.
The LAPD calls upon the NCIS team when a raid links a Mexican drug cartel to a wanted terrorist. Meanwhile, Sam’s most prized possession is stolen.
The NCIS team investigates the murder of a former Navy intelligence officer who had been living a double life and traveling overseas on false passports.
The NCIS team must determine whether a dishonorably discharged Marine is the target of an international set-up or if he committed murder
When a Navy ID is found on a dead body tied to a hazardous material smuggling case, NCIS is granted permission to investigate in Mexico and asked to help locate the missing materials.
After Sam’s undercover mission in Sudan turns deadly, Callen and the NCIS team must track down their missing agent before it is too late.
A botched assignment forces Hetty to fire Deeks and send him back to the LAPD. Meanwhile, an awkward goodbye between Kensi and Deeks leaves her with unexpected emotions for her old partner
The NCIS team must locate a classified device with the power to destroy Los Angeles that was stolen from a college research facility. Meanwhile, Sam tries to track down a highly sought-after Christmas present for his daughter, and Eric meets Nell’s parents.
A new Assistant Director is assigned to oversee LA operations for NCIS, the team begins to wonder what his intentions really are.
When a vehicle transporting Jada Khaled is ambushed, NCIS must track down the culprit to save her and their case. Meanwhile, Sam is forced to confront Jada for the first time since returning from Sudan.
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.
With Assistant Director Granger critiquing every move, the NCIS team must track down a chameleon-like killer who has evaded law enforcement agents, including their very own Special Agent G. Callen, across several countries.
The team searches for new evidence to prove Kensi Blye’s innocence after she is taken into custody as the lead suspect in a murder investigation involving her deceased father’s sniper unit.
The team continues to search for new evidence to prove Kensi Blye’s innocence after a private meeting involving her deceased father’s sniper unit turns deadly.
The NCIS: LA team investigates a shooting outside the Vietnamese Consulate just prior to an international conference at the venue that the Secretary of the Navy is scheduled to attend.
When the body of a Navy Intel Officer is found, evidence points to a team of Navy SEALs who are about to depart on a hostage rescue mission, leaving former Navy SEAL Sam Hanna to interrogate the group and possibly compromise the mission.
When a former Marine is suspected of creating a chemical bomb, the NCIS: LA team joins the FBI’s domestic terrorist task force including Operational Psychologist Nate Getz.
The joint NCIS: Los Angeles and Hawaii Five-0 task force travel from Hawaii to Los Angeles, when the lead suspect in the case moves to the mainland with a deadly virus in tow. Series crossover part 1 is Hawaii Five-0 (2010) S02E21.
Kensi and Deeks are sent undercover as married couple Melissa and Justin when evidence points to a Russian sleeper cell in a suburban neighborhood.
Callen and the team confront their vengeful adversary, the Chameleon, when an undercover case ignites a deadly mind game orchestrated by the criminal mastermind.