El sonido de los tambores
The episode is set on Earth one year after the events of "The Sound of Drums". In the episode, the alien time traveller the Master (John Simm) has conquered the Earth and enslaved its population to prepare warships for him to conquer the rest of the universe. The medical student Martha Jones (Freema Agyeman) spends the previous year travelling the planet as part of a plan to stop the Master.