A decomposed body is discovered in a tub of acid at a naval base and Ducky and Abby learn that the victim was a submariner. Gibbs discovers that there have been no reports of a sub crewmember missing, so he deduces that one of the subs has an imposter on board. With this new information, the team must find out which sub the man posing as the victim is in and what intentions he may have towards the sub.

When a Navy commander, who was a technical advisor to a civilian contractor for a Navy weapon, is found dead on the beach, the NCIS team investigates the murder using satellite technology.

An NCIS agent has been murdered while investigating a case and the team's job is to find out what happened...

A strange case for Gibbs and his team opens when a Navy Commendar dies after successful surgery. While researching through commander's past, the team finds out that he collected a lot of enemies lately and tracks down a ensign making him the prime suspect. Soon Abby realizes that they got the wrong man...

Erin Kendall (guest star Danica McKellar) claims to have seen a murder of a sailor in an apartment across from hers. Gibbs assigns the case to McGee who believes that he can resolve it himself. However, due to the lack of physical evidence, McGee turns to the team to help him...

Gibbs is ordered to talk to a convict that is about to be executed, in order to discover information about the place where he hid his victims, but when the plan doesn't work, the team must solve the case in their own way.

While on duty, McGee kills a man who is later discovered to be an undercover police officer. When Jenny decides to approve the investigation on McGee, the NCIS team is forced to prove that McGee is not guilty, pushing Gibbs' relationship with Jen to the limit. Meanwhile, Tony is troubled by his past.

While discovering an illegal automotive chop shop, the NCIS team stumbles upon a severed head of a Marine, hidden in one of the cars from the shop. When they find possible suspects, the team will have to find the rest of the body and find the murderer.

When a Pentagon cryptographer is found dead, the NCIS team has to discover whether the person was or wasn't a Pentagon mole, and if the person committed suicide. As the investigation continues, the team discovers that the person wasn't alone when she died, so someone must have murdered her. So, the team has to find the person, a mole, who murdered the cryptographer.

The NCIS team is called in to stop a naval officer from committing suicide by jumping off a rooftop, but when the suicide attempt turns into a murder, the NCIS team will have to find out who did it.

The NCIS team goes on a stakeout in a warehouse to catch a suspected thief of a high-tech naval radar, but they accidentally end up witnessing a murder. Meanwhile, Ducky hides a secret from the rest of the team.

While on an undercover mission, Ziva's life is put in grave danger when the serial killer she's been tracking becomes suspicious of her.

A distinguished senator asks Gibbs for help in solving the murder of a young female Naval officer.

During the week of Christmas, The Team is Forced to work overtime when they discover their prime suspect had been dead for 17 years.

When a fellow agent is murdered, the NCIS teams heads into the desert to locate a woman who might hold the answer to the mystery murder.

The team must take a second look into the death of a lieutenant after the blogger who accused them of a cover-up ends up dead.

Gibbs is worried about Tony's ability to handle his job when Tony's father turns out to be linked to their newest investigation, an assassination attempt on a foreign prince.

Gibbs and the team investigate the shooting of a Marine and uncovers more to his life than anyone would have ever imagined.

DiNozzo finds himself increasingly captivated by a woman he's never met while investigating the murder of her brother.

The team investigates a bomb tech's guarded personal life after she is attacked.

The team is surprised when Gibbs asks Tony's father to join them in a murder investigation.

A botched assassination attempt in Belgravia forces NCIS to protect the Defense Minister's daughter, who is studying in the U.S. and smitten with McGee. Meanwhile, Gibbs investigates the death of the U.S. Marine who was killed in the bombing.

The NCIS team tracks a Navy lieutenant's killer after a Pentagon security camera reveals a petty officer committing the crime. Meanwhile, Gibbs announces that Agent Barrett and her team will take over the Port-to-Port serial killer case.

The NCIS team searches for the person and motive behind a contract killer targeting a Navy Lieutenant Commander.

Meanwhile, Abby uncovers new information about her family after undergoing tests for a kidney donation.

After Anthony DiNozzo, Sr. is found in a car with a dead body in the trunk and no memory of the previous night, the NCIS team must figure out if he is capable of murder. Meanwhile, Tony is sidelined for this case and must go against orders to try and prove his father’s innocence.

Top-secret clearance from a Naval research laboratory is jeopardized when the murder of a Chief Petty Officer is connected to an international arms dealer. Meanwhile, Probationary Agent Ned Dorneget tries to butter up Gibbs in hopes of joining the team.

The NCIS investigation of a fire on a Navy vessel reveals evidence that elevates security at all U.S. Navy facilities worldwide. Meanwhile, DiNozzo and Ziva travel to Italy when an explosive device is found hidden on a Navy ship.

A petty officer is gunned down in a billionaire’s Ferrari and the investigation leads the NCIS team to discover a link to a man Gibbs was named after.

It’s Christmas time and Tony DiNozzo can’t decide if he’ll be naughty or nice when his dad, Anthony DiNozzo, Sr., comes to town for a visit. Meanwhile, the NCIS team is “following the money” in order to solve a murder investigation, and Abby is bursting with excitement over all the holiday festivities.

A media frenzy surrounding an unidentified criminal prompts Gibbs’ barber to question his son’s involvement and ask for Gibbs’ help in ruling out his son as a prime suspect.

In retaliation for the murders of Eli David and Jackie Vance, the NCIS team feverishly searches for Bodnar despite orders from Homeland Security to relinquish the case.

The NCIS team must rely on Twitter for a case involving a missing Navy Lieutenant. Meanwhile, McGee misplaces his badge but withholds the information from Gibbs and the authorities.

The team is forced to take another look at a hit-and-run murder case; McGee becomes suspicious of Tony's unusual behavior.

Someone winds up dead when DiNozzo confronts a man impersonating a Navy officer; DiNozzo's father needs to share a secret with his son.

When a Marine photographer disappears prior to providing his testimony in an Army court-martial hearing, the NCIS team investigates both the murder he witnessed as well as his current piece on military veterans who are homeless in the D.C. area. Meanwhile, Abby tries to help a young homeless woman reconnect with her family.

The NCIS team searches for a home-grown terrorist after a rescue mission in Syria reveals an American was involved in the capture of a social worker. Meanwhile, McGee and Bishop question DiNozzo’s unusual behavior.

After a Marine is found murdered in Quantico hours after calling Gibbs to discuss a possible case, Bishop and McGee go undercover as a married couple to run surveillance on a Marine Lieutenant and his wife.

When Gibbs spots the brother of an "NCIS Most Wanted" suspect, he takes the opportunity to assume his former alias and go undercover with their infamous anti-government militia. This leaves the NCIS team to piece together where and what Gibbs is up to. Meanwhile, Bishop and Reeves partner up on an off-the-books investigation.

When a Navy SEAL vanishes during an unsanctioned trip, Gibbs, McGee and Torres travel to an unpopulated area in Paraguay that's teeming with violent rebels.

Sloane is adamant that a man who held her hostage and tortured her years ago in Afghanistan, and was believed to have been killed following her rescue, is alive and in D.C. Also, Vance and Gibbs fear Sloane is willing to risk everything to destroy this man.

When the lead suspect of an unsolved and high-profile robbery case is released from prison, the NCIS team resumes their investigation with an undercover stakeout.