The 500th episode of "NCIS" featured a unique reunion between NCIS Director Leon Vance and a younger version of Ducky Mallard, who appeared in spirit form and helped usher Vance into the afterlife. Since both characters are now dead, it is unlikely fans will ever see this reunion again. The episode follows the death of Vance (Rocky Carroll) and the sister of Billy Fuentes (Austin Marques), who was framed for a murder related to a weapons-smuggling operation. Adam Campbell, who has previously played Ducky in guest-starring episodes for the show, has become a key character for NCIS and is becoming a useful tool for the team.