In the fourth episode of the 12-part story "The Dalek Masterplan," the TARDIS crew persists in its efforts to prevent the Daleks from unleashing their doomsday weapon, the Time Destructor. Captured by the villains, Katarina (Adrienne Hill) nonetheless manages to save the lives of her traveling companions. Meanwhile, Bret (Nicholas Courtney) is faced with a decision that profoundly alters his relationship with the rest of the crew members. Written by Terry Nation, "The Traitors" originally aired on December 4, 1965; this episode apparently no longer exists. ~ Hal Erickson, Rovi