Led by Special Agent Leroy Jethro Gibbs, this squad of highly trained N.C.I.S. agents proves it is willing to make the ultimate sacrifice to thwart espionage and terrorism around the world.

Season four continues the adventures of a cutting-edge crew of special agents who operate outside the government's chain of command. Led by Leroy Jethro Gibbs, a former Marine whose skills as an investigator are unmatched, this highly trained, tight-knit team travels the world investigating murder, espionage, and terrorism.

NCIS Special Agent Jethro Gibbs leads his team to investigate all crimes dealing with the U.S. Navy or U.S. Marine Corps. The team continues to deal with a death of one of its own while being broken up by the new director; they find a mole within their ranks; murder at a Marine base; a home invasion right before Christmas; McGee becomes a hostage at a womens' prison; and Abby is recruited to help out when a government scientist goes missing.

Brennan's uncanny forensic skills help resolve even grislier cases, including a retirement home murder, a possible death by robot, and the slaying of close friend. Along the way, family tragedy strikes and Booth lands in the crosshairs of a serial killer. The fascinating storylines, heart and humor of these twelve episodes wrap of the final season of this hit series.