The Rookie world is expanding.Niecy Nash joins the fray as Simone Clark, the oldest rookie in the FBI Academy, for a two-hour backdoor pilot setting the table for a potential spinoff. In Nash's debut episode, which airs Sunday, Officer John Nolan (Nathan Fillion) and the Los Angeles division of the FBI enlist the help of FBI trainee Clark when one of her former students is suspected of terrorism following an explosion at a local power station.«Simone is so fun to play,» Nash tells ET's Rachel Smith of her character.