Joe Spano reprises his recurring guest role as Tobias "T.C." Fornell, who enlists the help of Gibbs (Mark Harmon) to help him track down the drug ring that supplied illegal substances to the former's daughter in "Sturgeon Season," the Season 18 premiere. Meanwhile, the rest of the team tries to find out what happened to a cadaver that inexplicably vanished from the NCIS autopsy room. Victoria Platt and Brian Stepanek guest star; Sean Murray, Emily Wickersham and Wilmer Valderrama also star.