Gibbs and McGee are shot down in a Naval helicopter over remote parts of Russia while on a mission to escort an NCIS computer geek safely home. Meanwhile, the gang at home anxiously work to help bring them all home safely.
A Navy Commander is murdered near the White House, it is learned that he was on his way to talk to the President. Gibbs and his team must determine if it is because of his relationship with the President or because of his marital problems.
Flashbacks into his past help tell the tale for Dr. Mallard as he and Bishop travel to England in search of answers to find out why an Englishman murdered in the United States would have a list of deceased Navy men on his person.
After a scientist is decapitated by a strangulation device in a park, Gibbs and his team search for the woman who was her former research partner in Russia in order to learn who is behind her murder. They learn it may be a familiar foe.
While the NCIS team is on a training exercise with CGIS Special Agent Abigail Borin, Gibbs spots a man overboard. It leads him to board another ship called The San Dominick, and he soon discovers that it has been taken over by pirates.
The wife of a Navy Seal is murdered, the NCIS team discovers she has a background in criminal forensics and recently visited a serial killer in prison seeking his help with another sociopath. Gibbs and company must figure out it is.
While investigating the death of a retired Marine Master Sergeant, Gibbs and the NCIS team discover there is a possibility that his death may be connected to another Marine who was MIA from the Vietnam War.
A former Navy hospital corpsman gives aid to the victims of a wreck; local officials arrest her for practicing medicine without a license; Gibbs and company find the other driver, his killer, and a lawyer who makes a deal for the corpsman.
On the eve of Thanksgiving, DiNozzo and Bishop experience a weather delay at the D.C airport when Gibbs informs them of an elevated terror threat specific to area airports. An impostor posing as an air marshal leads them to the real threat.
Tis the season to be hacking. In a Christmas letter to his father, McGee describes in detail a case in which he, Gibbs and the rest of the NCIS team investigate the hackers who are responsible for the Internet going down in the D.C. area.
DiNozzo returns to the military academy he attended as a teenager after a murdered Marine and alumni of the school is found clutching the photo of a current student. Also, Bishop and her husband invite Gibbs and the team out for a special dinner.
Gibbs and the NCIS team continue to track down the Russian terrorist Sergei after two young Marines are killed in a bombing. Agent Fornell struggles to cope with the recent shooting death of his ex-wife at the hands of Sergei.