Doctor Who (series 4) Astrid Peth, who died during the events of the episode. The companions in the regular series had all been in the lead companion role previously: the primary role of Donna Noble, who was introduced in "The Runaway Bride", was played by Catherine Tate for all thirteen episodes. Her return was announced by the BBC on 3 July 2007. Freema Agyeman, who portrayed the Doctor's companion Martha Jones in series three, returned for "The Sontaran Stratagem", "The Poison Sky", "The Doctor's Daughter", "The Stolen Earth" and "Journey's End". Billie Piper, who played Rose Tyler from the first episode of the new
Rose Tyler history, when she attempts to save the life of her father Pete Tyler (Shaun Dingwall), who had died when she was a baby. Throughout these journeys, she and the Doctor are haunted by two mysterious recurring words: 'Bad Wolf'. Rose, the Doctor, and new companion Captain Jack (John Barrowman) come to understand the meaning of this phrase when they encounter an unstoppable army of evil alien Daleks on the space station Satellite 5. To return to the Doctor after he sends her home to Earth in series finale "The Parting of the Ways", Rose tears open the console of the