
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.

The Coast Guard Investigative Service works with the NCIS team when an explosion occurs on an oil rig; a mysterious prankster targets the team.

NCIS discovers a connection between McGee's grandmother (Lily Tomlin) and the murder of a Navy lieutenant.

When family matters force Gibbs to leave mid-case, McGee and Tony argue over who should lead the murder investigation in his place.

After a firefight and a concussion wreak havoc on Tony's mind, Tony needs Gibbs to help him regain his memories of the investigation.