In the third episode of the seven-part story arc "The Daleks," the Doctor (William Hartnell), Ian (William Russell), and Susan (Carole Ann Ford) join forces to rescue Barbara (Jacqueline Hill) from the mutant Daleks. In his efforts to find out why the Daleks want to resume their nuclear war with the humanoid Thals, the Doctor discovers that the mutants need radiation to survive. Unfortunately, this will require the utter descruction of Skaro by a neutron bomb. Written by Terry Nation, "The Survivors" first aired on January 4, 1964. ~ Hal Erickson, Rovi