The NCIS team's LAPD liaison officer, Detective Marty Deeks, goes missing while undercover, right after the subject of his investigation is killed by a bomb planted in their car. LAPD Detective Jess Traynor, Deeks's partner, dies from a similar car bomb just after briefing NCIS. The team is tasked to find the missing detective. Guest starring: Michael Harney, Jon Sklaroff, Meta Golding
An NCIS undercover agent is assassinated while in Cyprus investigating illegal arms sales to Chechen extremists. The same hit team is later detected arriving in Los Angeles, and the NCIS Los Angeles team is in a race against the clock to stop the assassins from killing their next target, a suburban housewife who is more than she appears to be. Guest starring: Daniel Hugh Kelly, Liane Balaban, Steven Brand, Waleed Zuaiter, Hrach Titizian, Allan Louis, Andrea C. Pearson
Four Marines are ambushed while participating in a joint DEA-Marine task force interdicting Mexican criminals along the U.S.-Mexico border. The NCIS team works to recover the captured marines and uncover the mastermind behind the operation: a textile manufacturer who wants the US military to go to war with the cartels so they will stop interfering in his factories south of the border. Guest starring: Alan Ruck, Billy Magnussen, Vincent Laresca, Graham Shiels, Bruno Gunn
The NCIS team investigates the murder of a sailor with top-level security clearance after he is found dead and missing a hand in a Rodeo Drive parking lot. The case takes a turn after it is discovered he was selling artifacts that were looted from a museum during his tour in Iraq. Guest starring: Navid Negahban, Matt Cohen, Austin Stowell, Camryn Grimes, Naz Deravian, Aalok Mehta, Jarrod Crawford, Kinsey McLean
When the teenaged daughter of a Navy commander is kidnapped by what appears to be a serial killer who buries his victims alive, the team needs to determine whether he is the target of blackmail for military secrets or if the crime is random. Sam takes the case personally after getting flashbacks of being buried alive while doing a mission in Bosnia as a Navy SEAL. Guest starring: Alicia Coppola, Brian McNamara, Vincent Irizarry, Louis Mandylor, Elaine Hendrix, Haley Ramm, Michael Holden, Tyler N
After a downtown Navy Recruitment Center is held hostage by Callen's ex-CIA partner and undercover wife, Tracy Keller (Marisol Nichols), he realises she is searching for him for help. Tracy explains she is on the verge of exposing a group of corrupt FBI Agents and their arms dealer contact in the aim of recovering stolen missiles. But not everything is as it seems, and the NCIS team worry whether Callen has fallen under the charms of his ex-wife. Guest starring: Marisol Nichols, Stephen Snedden,
A State Department employee and plastic surgeon are murdered. The team discovers a terrorist cell has had their faces surgically altered. They must find the one person who can identify them and foil an impending terrorist attack. Guest starring: Kate Levering, Christopher Judge, Carlos Lacámara, Greg Collins, Lynn Chen, Cassandra Jean
The team investigates the murder of a retired Delta Force operator who previously worked with a Marine SOCOM unit tasked to capture high-priority targets in Afghanistan. Guest starring: Dariush Kashani, Stephen Amell, Brett Del Buono, Mary Pat Gleason
The murder of an arms dealer has Hetty and the NCIS team searching for his missing book of top-secret information. The episode ends with Hetty discovering that her "husband", Branston Cole, a security guard, and a nurse have all been killed. Guest starring: Jürgen Prochnow, Mark Pinter, Scott Connors
In the aftermath of Cole's death, Hetty and the NCIS team continue to search for a book that was the target of various intelligence agencies, both foreign and domestic. Things heat up when various spies and agencies from numerous countries begin heading to Los Angeles, forcing the team to race against time to stop the respective gangs from tearing LA apart in their search for the book. The conclusion of a two-part episode. Guest starring: Jürgen Prochnow, Chris McKenna, Nico Evers-Swindell, Sama
When two men are killed in a shootout, the NCIS team must rely on a former Navy intelligence officer suffering from PTSD to help them solve the case. Guest starring: David Hoflin, Azita Ghanizada, Charles Carpenter, Thomas Hobson, Beth Behrs
The NCIS team uncovers an experimental Navy tracking system when a body containing a top-secret residue is stolen from an autopsy room. It is discovered that the thieves merely needed the eyes of the victim in order to access a locked hospital storage room in order to steal radioactive material. Meanwhile, Callen challenges Hetty on the rock wall. Guest starring: Ned Vaughn, Aaron Abrams, Lois Atkins, Izzy Diaz
The NCIS team sets out to find the individual responsible for stealing a classified Pentagon document before the file's decryption code is cracked by the wrong party. Guest starring: Erik Jensen, Anna Campbell, Cliff Simon, Bre Blair, Drew Rausch, Leslie Odom Jr., Falk Hentschel
As G goes off the grid for a day for personal reasons, Sam goes undercover in prison in an attempt to infiltrate a Yemen-based terrorist group by getting close to its leader, another inmate. Guest starring: Hakeem Kae-Kazim, Rick Ravanello, Jason Matthew Smith
What begins as a break-in at G's house leads to a pursuit of black market microchips, and a series of double-crosses. Callen agrees to investigate an Indian "slum dog millionaire" who happens to be Arkady Kolcheck's business rival. Kolcheck also promises Callen to shed some light on the cemetery incident (season 1 finale "Callen, G"). Guest starring: Pej Vahdat, Nickolai Stoilov, Marcuis Harris
Callen and Sam go undercover with the California Highway Patrol to investigate a corrupt group of CHiPs officers and their connection to missing weapons. But a routine job takes a dramatic turn, and a stolen nuclear warhead sends the OSP team scrambling to recover the bomb. Guest starring: Sophina Brown, Ed Quinn, Connor Trinneer, Johnny Sneed, Mitch Longley, Desiree Hall, Lewis Tan
LAPD–NCIS Liaison Detective Marty Deeks's routine is thrown when he interrupts a convenience-store robbery and is shot, but the NCIS team finds out Deeks was targeted, but not to kill him, instead to lure out NCIS Junior Special Agent Kensi Blye by Vakar (first mentioned in "Black Widow"). Guest starring: Brad Beyer, Vasili Bogazianos, Sarayu Rao, Justin Huen, Rafael Petardi
The story arc that started in the episode "Lockup" is concluded as Sam is sent on an undercover mission to Yemen. But the stakes are raised when it's revealed that the terrorist group has taken a young seven-year-old boy hostage and things get even worse for the team when it's discovered Nate's cover has been compromised which means that Sam has been exposed as well, forcing Callen, Sam and Nate into a fight for survival against terrorists who want them dead. Guest starring: Hakeem Kae-Kazim, Ji
It's a race against time as the team attempts to foil an assassination plot against a Venezuelan politician on U.S. soil. Guest starring: Joshua Bitton, Myndy Crist, Taylor Sheridan, Eduardo Yáñez
A secure facility on a marine base becomes compromised, causing Kensi to go undercover as a thief in the hope of finding out what a world-class thief planned to steal from the secure facility without having her cover blown. Guest starring: Victor Webster, Amy Sloan, Kyle Davis
After a rocket engine expert is killed, OSP tech operator Eric Beale goes undercover for the first time to ensure that the classified technology used to build satellites is safe. Guest starring: Harry Van Gorkum, Wynn Everett, Gideon Emery, Danny Jacobs
To protect his best friend and primary informant from a group of arms traffickers, Deeks must go deep undercover to an old alias. Guest starring: Channon Roe, Evan Parke, Erin Foster, Joe Egender, Cathy Lind Hayes, Mo Gallini
The stolen canisters from "Overwatch" resurface after a Navy SEAL imposter is set ablaze. Hetty sets her affairs in order as she prepares to resign from NCIS. Guest starring: Blake Gibbons, Kristen Hager, Dean Chekvala, Jake Richardson, Charlene Amoia, Collins Pennie, Bruno Verdoni, Max Bunzel
Hetty's resignation from NCIS prompts Callen and the team to initiate an investigation to find her. It is revealed that she has been working on a case involving Callen's mysterious past, and that she herself is a member of the family that has been trying to kill him for years. Guest starring: Cristine Rose, Robin Atkin Downes, Adam Tsekhman, Jilon VanOver, Michael G. Welch