第 3 季 共 24 集
播出时间：2011年9月21日
第 1 集 Lange, H.
播出时间：2011年9月21日
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. Hetty confronts Alexa, matriach of the Comescu family, and it is revealed that Callen's grandfather was an OSS agent who killed several members of the family; the Comescus retaliated, killing his mother, but leaving Callen and his sister alive. Meanwhile, Eric and Nell discover that Lauren Hunter, the Office of Special Projects' Operations Manager, is a member of the Comescus. It is ultimately revealed that Hunter assumed the identity of Ilena Vadim - a member of the family who distanced herself from them - to infiltrate the Comescu family; the other members of the team are unaware of her exact allegiance until she kills Alexa and retrieves a laptop from the Comescu beach house. The episode ends in a cliffhanger with the other characters realizing that Hetty has been shot by Alexa. She then collapses to the ground, her fate unknown.
第 2 集 Cyber Threat
播出时间：2011年9月28日
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.
第 3 集 Backstopped
播出时间：2011年10月5日
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.
第 4 集 Deadline
播出时间：2011年10月12日
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.
第 5 集 Sacrifice
播出时间：2011年10月19日
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.
第 6 集 Lone Wolf
播出时间：2011年10月26日
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.
第 7 集 Honor
播出时间：2011年11月2日
The NCIS team must determine whether a dishonorably discharged Marine is the target of an international set-up or if he committed murder
第 8 集 Greed
播出时间：2011年11月9日
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.
第 9 集 Betrayal
播出时间：2011年11月16日
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.
第 10 集 The Debt
播出时间：2011年11月23日
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
第 11 集 Higher Power
播出时间：2011年12月14日
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.
第 12 集 The Watchers
播出时间：2012年1月4日
A new Assistant Director is assigned to oversee LA operations for NCIS, the team begins to wonder what his intentions really are.
第 13 集 Exit Strategy
播出时间：2012年1月11日
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.
第 14 集 Partners
播出时间：2012年2月8日
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.
第 15 集 Crimeleon
播出时间：2012年2月15日
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.
第 16 集 Blye, K. (1)
播出时间：2012年2月22日
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.
第 17 集 Blye, K. (2)
播出时间：2012年2月29日
The NCIS: LA 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.
第 18 集 The Dragon and the Fairy
播出时间：2012年3月21日
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.
第 19 集 Vengeance
播出时间：2012年3月28日
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.
第 20 集 Patriot Acts
播出时间：2012年4月11日
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.
第 21 集 Touch of Death (2)
播出时间：2012年5月2日
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.
第 22 集 Neighborhood Watch
播出时间：2012年5月9日
Kensi and Deeks are sent undercover as married couple Melissa and Justin when evidence points to a Russian sleeper cell in a suburban neighborhood.
第 23 集 Sans Voir (1)
播出时间：2012年5月16日
Callen and the NCIS: LA team confront their vengeful adversary, the Chameleon, when an undercover case ignites a deadly mind game orchestrated by the criminal mastermind.
第 24 集 Sans Voir (2)
播出时间：2012年5月16日
The L.A. team is drawn into a deadly mind game against a master criminal motivated by Revenge.
