
Naval Criminal Investigative Service Special Agent Leroy Jethro Gibbs leads a group of colorful personalities in investigating crimes -- ranging from murder and espionage to terrorism -- that have evidence connected to Navy and Marine Corps personnel. The team includes MIT graduate Timothy McGee, Ellie Bishop, who specializes in international threat assessment, charismatic and unpredictable Nick Torres, and forensic psychologist Jack Sloane. Dr. Donald "Ducky" Mallard brings his vast experience in forensics into play to help solve cases.

Cassidy (Jessica Steen) blames herself when the team learns that a tip on terrorist activity was a trap that resulted in the deaths of two agents.

After human remains are discovered at a construction site, NCIS investigates the murder of a Marine major believed to have been killed in the 9/11 attack on the Pentagon; a personal history with the victim drives Gibbs to solve the crime.

After entering cold case DNA into the system, Kasie solves a 30-year-old murder case, but a loophole in the legal system may set the suspect free; McGee visits an elite technology company in Silicon Valley that is offering him a high-paid position.

After NCIS finds a secret government bank account that's funding a nationwide network of vigilante justice, the team must determine who is acting as judge and jury.