Led by Special Agent Leroy Jethro Gibbs (Mark Harmon), the members of the Naval Criminal Investigative Service use their expert skills to crack the trickiest military-related crimes in this CBS series that crosses "JAG" with "CSI." The addition of a new NCIS director, Jennifer Shepard (Lauren Holly), shakes things up this season, especially considering her romantic history with Gibbs. Michael Weatherly, Pauley Perrette and Sean Murray co-star.