||Deep Trouble, Part 2
||29 Sept. 2014
||Season Premiere. Callen and Sam fight for their lives in the aftermath of being trapped on board a submarine with two terrorists as the OSP team continue searching for them.
||6 Oct. 2014
||The team discovers one of them has been compromised during a murder investigation. Hetty is under investigation, and the DOJ investigates the team.
||13 Oct. 2014
||One of Hetty's houses is attacked, resulting in the death of her bodyguard. As the DOJ investigation continues, the team is forced to balance eluding their questions with finding who was responsible. Ultimately, Vance reveals to Hetty that the investigation into OSP was a ploy to get Hetty out of Los Angeles, protecting her from a leak inside of the agency and a subsequent attempt on her life, leading the team to discover that an old enemy (Matthias from season 2's "Absolution") was responsible for the attempt, and the episode ends with Callen threatening to make good on the promise they made to him before vowing that they will hunt down Matthias and kill him.
||The 3rd Choir
||October 20th 2014
||The team finds itself in danger as the mole remains inside of the agency. Nate returns to help Nell deal with the aftermath of her first kill while the OSP center itself turns into a battleground when Matthias arrives to kill Hetty.
||October 27th 2014
||Callen and Sam go to Mexico to find a DOD employee.
||November 3rd 2014
||Sam is arrested for murder, and the rest of the team try to prove his innocence despite being stone-walled by the FBI and a U.S. Attorney. It turns out a former Marine student of Sam's was running a large scale identity theft operation, and he framed Sam in the murder of his accountant.
||November 10th 2014
||When a Greek terrorist is killed using a drone in Los Angeles, the OSP is asked to investigate. It turns out an anarchist group had hired him to build a drone missile and then killed him using the prototype
||The Grey Man
||November 17th 2014
||An AWOL Marine/CIA agent is found dead, and the team goes to investigate his death, leading them to a high-profile drug lord about to be extradited to the U.S. and a major secret the deceased was holding about one of the lead attorneys on the case.
||November 24th 2014
||When Granger is put in the hospital, OSP is on lockdown as everybody becomes a suspect of being the leak.
||December 08th 2014
||When a paparazzo is killed outside the house of a high-ranking CIA officer and a Marine colonel, the team discovers the attack is one in a string of attacks on parents with children in military school. Meanwhile, the case has Sam to start thinking about his own father
||December 15th 2014
||When Callen's girlfriend becomes a hostage following a security company's robbery, the team's search for the robbers leads Callen's girlfriend to find out his true occupation. The team discusses Christmas plans.
||January 05th 2015
||Terrorists take hostages at an office building where Callen is undercover to investigate an arms dealer. Callen's team tries to extract him, only to find the building is wired with explosives.
||In The Line of Duty
||January 19th 2015
||After an attack on the U.S. Consulate in Tunisia, Callen and Sam go to the crime scene to investigate the death of two officers (one of which was a close friend of Sam's) and soon discover that perhaps the Ambassador was not the intended target of the attackers, who have now entered the United States.
||February 02th 2015
||When the victim of a car crash is discovered to have a lethal strain of anthrax, Callen and Sam are sent to Mexico to locate the virus's origin while Kensi and Deeks try to stop the anthrax from being utilized in an attack.
||Forest For The Trees
||February 09th 2015
||When a tip regarding a missing NSA analyst results in Callen and Sam being abducted, Kensi and Deeks investigate if their kidnapping was related to Granger's impending meeting with an ISIS informant.
||February 23th 2015
||When on a mission to bring in an Indian defector, Sam is shot by a sniper, leading the team to work with Jemadar Thapa (from season 5's "The Frozen Lake") to find the culprit, leading to a face-off with a team of rogue Gurkha agents and questions about the defector's true agenda. Meanwhile, Kensi and Deeks have an argument.
||March 09th 2015
||When an Afghan soldier brought to America for DEA training is murdered, the OSP team finds themselves tracking down his two comrades who have been targeted for the information they know about the Afghan military.
||March 23th 2015
||After a successful sting operation, three FBI agents are killed in a sudden explosion, resulting in OSP being assigned to investigate. Upon investigating, they learn that the agents were killed by a hidden bomb and that the attack isn't the only one - leaving the team racing against the clock to identify where the second attack is being held. Meanwhile, for the investigation, Hetty pairs Kensi with Sam and Callen with Deeks, but for a reason neither Kensi nor Deeks can guess.
||Blaze of Glory
||March 30th 2015
||After a Navy test missile is hijacked and used to destroy a civilian boat, the team is tasked with ensuring other Navy weapon systems haven't been compromised, and the team's investigation leads them to an internal conflict inside of a hackers' organization. Meanwhile, when a college graduate agent comes down to OSP to assist, Eric begins to hit it off with her, making Nell jealous.
||April 13th 2015
||Callen is returned to his undercover assignment in prison to infiltrate a White supremacist group suspected of holding stolen nuclear material, and soon finds himself in the midst of a bank robbery with trigger-happy "brothers".
||April 20th 2015
||Callen and Sam are surprised when a murder victim turns up alive and wants their help. The NCIS OSP team investigates and finds that someone has broken the rules of sanctions against Russia. Arkady's in trouble again.
||Field of Fire
||April 27th 2015
||The team searches for a former Marine and expert sniper who escaped a veterans hospital when they discover his connection to the leader of an extremist group. Also, the case reminds Kensi of her past as a sniper.
||May 11th 2015
||Callen and Sam search for answers when they find dead crew members from the missing oil tanker used in Arkady’s deal with Russia, and also discover Arkady’s personal connection to the ship.
||May 18th 2015
||An ongoing case leads Callen, Sam, Deeks and Kensi to Moscow, where the team must assume multiple undercover identities to locate their suspects. Also, Callen uncovers new information regarding his father.