With the inauguration of its second season, the popular procedural streamlines its series title, forsaking the cumbersome Navy NCIS: Naval Criminal Investigative Service for the more succinct NCIS. Joining series regulars Mark Harmon (Leroy Jethro Gibbs), Shana Alexander (Kate Todd), Michael Weatherly (Tony DiNozzo), Pauley Perrette (Abby Sciuto) and David McCallum ("Ducky" Mallard) is former guest actor Sean Murray as MIT-educated lab tech Tim McGee, who is invited to join the NCI team by head man Gibbs himself. Amidst such story elements as kidnappings, serial killers, serial rapists, crop circles, mob hits, transsexuals, disembodied eyeballs and bikini contests, the second season permits the viewer to learn just a tiny bit more about the clouded past lives of Leroy Jethro Gibbs and Dr. Donald "Ducky" Mallard; we also meet for the first time Ducky's 96-year-old mother, played by Nina Foch. And, given the world climate, it isn't surprising that this season's episodes would make numerous pointed references to the Iraq War and the general unrest in the Middle East. The devastating season finale "Twilight" marks the return of the team's most formidable adversary, double agent and terrorist Ari (Rudolf Martin), who among other acts of villainy cold-bloodedly murders one of NCIS' most popular leading characters.