The NCIS team must learn to work without Gibbs, who has retired; Ziva witnesses a political assassination and the FBI wants her.
NCIS temporarily reinstates Gibbs when an escaped convict threatens his friend's life.
While searching the abandoned and bloody car of a missing Navy lieutenant, the team learns she had been profiling men to find the perfect mate.
The team is called to the scene of the murder of a petty officer who was part of an undercover arms operation.
The team investigates the death of a missing lance corporal, whose body was buried in the backyard of a vacant house and then exhumed.
The NCIS team investigates when a Marine is attacked in his home and his daughter is kidnapped on Halloween; Abby's Halloween costume leaves McGee and Tony speechless.
Gibbs' team works with the Army Criminal Investigative Unit to investigate a suspected terrorist attack that killed a Marine colonel at a military country club.
Suspicious activity surrounds a decorated Marine veteran's death, leading the NCIS team to try to clear his name.
McGee takes things into his own hands, forgoing NCIS procedure, when his sister arrives on his doorstep, bloodied and confused.
The NCIS team joins forces with the FBI when a burned and mummified body found in a furnace turns out to be that of a serial killer the FBI had been chasing for more than a decade.
A highly classified robotic vehicle causes the death of a Navy lieutenant working on a high-level project for the Department of Defense; Tony's secretive trips to the hospital worry Ziva.
The team battles local biases when it investigates the murder of a high-level Marine intelligence officer found in a small-town motel room.
The NCIS team must track down a wanted terrorist (Enzo Cilenti) who has obtained a missing chemical weapon before he carries out his plan to attack major U.S. cities.
Ducky goes under cover to stop the illegal sale of the Navy's top-secret weapons system to a high-priority arms dealer (Armand Assante).
When a young sailor's body is found in an abandoned building in a seedy part of town, an ominous message written in blood leads the team to switch gears to find the killer.
The NCIS team suspects foul play when a Navy lieutenant is the victim of radiation poisoning; Tony sees a softer side of Ziva.
When an explosion at a military cemetery's mausoleum reveals a cache of dismembered human remains, the team searches for a potential serial killer.
With a young Marine on life support, the team tracks his movements in the days leading up to his being left for dead.
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.
When a petty officer on whom McGee based a character for his latest book is murdered, McGee must figure out who could have accessed his secret manuscript.
Gibbs and the team must take action after the director's risky solo meeting with an informant ends with a death.
The team turns to a blind photographer (John Billingsley) to use his heightened senses of hearing and smell to re-create a crime scene and track down a petty officer's killer.
Gibbs leads the investigation into a murder victim found in a taxi headed to NCIS headquarters; Jenny discovers a secret about her past.