'NCIS' Stars Vanessa Lachey, LL Cool J, Chris O'Donnell and More Dish on Crossover Event (Exclusive)

The 'NCIS,' 'NCIS: LA,' 'NCIS: Hawaii' three-hour crossover event begins Monday, Jan. 9 at 8 p.m. ET/PT on CBS. The 'NCIS'-verse crossover will center around a very personal, high-stakes case to take down a mysterious hitman. Team members from the different NCIS divisions come together in Washington, D.C., to celebrate a beloved FLETC (Federal Law Enforcement Training Center) professor who taught multiple members of each of the squads. On the eve of the celebration, the professor is found dead of an apparent suicide and his former students immediately suspect foul play. While investigating his past, they uncover a mysterious hitman, and the more they dig into it, the bigger the targets on their backs become. Members of the team are suddenly kidnapped and all the agents must come together to take down the assassin and save their own.