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
Doctor Who: Children in Need coordinates for her council estate on Christmas Eve, offering her the choice to stay with her mother, Jackie Tyler, or continue her travels with him. Suddenly, the Doctor suffers a form of seizure, expelling glowing energy from his mouth, and the TARDIS shudders as if in sympathetic response. The Doctor tells Rose the regeneration is going wrong and starts to act maniacally, throwing switches on the TARDIS console and ranting about increasing speed as the sounds of the Cloister Bell start ringing through the console room. As Rose hangs on to the console for dear life, the TARDIS heads for