Gibbs and McGee travel to Russia to safely escort home an NCIS computer engineer connected to classified intel, but their mission is compromised and they are forced to go off the grid while hunted by a Russian mercenary group. Meanwhile, the team in D.C. frantically uses every asset and inter-agency contact they have in an attempt to locate their missing team members.
When a Navy Lieutenant is killed on his way to a private meeting with the President, the NCIS team must determine if the murder was part of a recent stream of muggings in the area or a targeted hit to keep intel secret.
When an NCIS case reveals a connection to Ducky’s estranged childhood best friend, he and Special Agent Bishop travel to London for interviews with family and co-workers of his friend. While there, Ducky finds himself reminiscing about the choices he made in his past and the subsequent impact they had on his adult life.
The Secretary of the Navy assigns the NCIS team to a joint terrorism task force after a Naval research scientist is murdered and the lead suspect is wanted by the Russian government. In order to get a jump on the case, Gibbs has DiNozzo run interference with the leader of the task force, FBI Agent Leia Pendergast.
During a joint Coast Guard and NCIS training exercise at sea, Gibbs and CGIS Agent Borin spot a deceased man overboard, who is discovered to be a missing crew member from a ship 60 nautical miles away. Upon boarding the ship for questioning, Gibbs finds himself on a vessel that has been commandeered by pirates.
A Navy commander's wife is discovered dead and the team have to determine whether her death is linked to her profession as a therapist or an act of terrorism after they see her husband's name on a jihadist target list.
The team uncover a fraudulent charity who are targeting people looking for missing military personnel.
While the NCIS team investigates the cause of a hit and run accident that resulted in the death of a Petty Officer, Gibbs searches for a way to clear a Navy Hospital Corpsman, who has served two medical tours in Afghanistan, after she’s indicted for illegally providing medical aid to the victims of the crash, even though the surviving victims swear by her life-saving techniques.
Whilst they wait at the Dulles airport due to bad weather, DiNozzo, Bishop and her husband Jake work an NCIS case featuring an terrorist threat at Northeast airports during the peak Thanksgiving travel period.
The team work with three imprisoned cyberterrorists after the city's Internet is shutdown.
The NCIS team investigate a series of crime scenes that appear to be copycats of previous cases. Meanwhile, two of Gibbs' ex-wives show up at a crime scene to discuss something important with him.
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.