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
Turn Left (Doctor Who) what Donna will become. The Doctor hears Donna scream and turns up in the booth. After examining the beetle, the Doctor comments on how it was odd for an alternative universe to form around her, explaining that the beetle worked for The Trickster with the job of changing people's lives in various ways. His remarks cause Donna to recall Rose and her message, which she delivers to the Doctor. Rose had told her two words: "Bad Wolf". A panicked Doctor, realising who Donna must have met, runs out of the room to find the words "Bad Wolf" written everywhere once