The season opener of NCIS begins a story arc that fans won't want to miss and provides the shocking answer as to why the new director, Leon Vance, really split up Gibbs' team. The series resumes four months after the bombshell that sent Ziva back to Israel, McGee into the cyber unit and DiNozzo on a new assignment as an Agent Afloat aboard a United States aircraft carrier. The sixth season of NCIS is full of surprises including some revealing facts about Gibbs' past as well as Gibbs going toe to toe with his new boss.