S03E12: 'The Sound of Drums'

Captain Jack uses his vortex manipulator to enable him, The Doctor and Martha to return to present day Earth, where they soon realise that The Master has taken the guise of Harold Saxon - Britain's new Prime Minister. They learn that he has control of a mobile phone network called Archangel.

During a cabinet meeting, Saxon unleashes a lethal gas, putting on a gas mask himself, with everyone else in the room killed. A journalist investigating Saxon believes she has evidence that his background is pure fabrication. When she confronts Saxon's wife Lucy, The Master appears and summons these metallic spheres - the Toclafane - who proceed to savagely kill the hack.

Saxon/The Master announces to the public that Earth will make contact with a new species the following day. In his address he makes reference to a 'medical student' - meaning Martha - and the time travelling trio discover an explosive attached to the back of the television in her flat when watching. They fortunately escape just in time.

A blonde lady working for Saxon tries to use Martha's mother Francine to lure her daughter into a trap, but her father Clive shouts down the phone to warn her away. The entire Jones family is then arrested, prompting Martha to head to her mother's house. The police fire at her and she, along with The Doctor and Jack, manage to escape.

Whilst Martha is on the phone warning her holidaying brother Leo, The Master's voice comes on the line and he then talks with The Doctor, revealing that the Time Lords resurrected him to help them in the Time War. He subsequently fled. The Doctor then learns that he and his two associates are Britain's most wanted criminals.

The Doctor soon discovers that The Master has used the Archangel network to send out subliminal drum-like messages that persuade people to support him without question. He then uses the Tardis key to give the trio a perception filter, meaning they can move around without being seen, in theory.

Saxon meets the US President Arthur Winters, who tries to take control of the planned meeting with the Toclafane despite saxon's defiance. Saxon then parades Martha's family in the open, trying to lure the fugitives out. They board an aircraft carrier called the Valiant, with the trio following using Jack's vortex manipulator. The Tardis is then found by its rightful owner, who finds that it has been 'cannibalised' and used to avert any time paradoxes.

With the eyes of the world watching Saxon about to present the new species to the Earth, the US President tries to take control and The Master reveals himself, with the Toclafane killing the American. The Doctor steps in but is captured, whilst the immortal Jack is killed but comes back to life. Using technology from Lazarus's Laboratory, as encountered by The Doctor previously, The Master uses a device to make his rival age by 100 years.

Helpless, the Time Lord watches as swarms of Toclafane come through the sky and are given the order to wipe out 10% of the planet's population. Martha however, manages to use Jack's vortex manipulator to escape. But what can she do to save the world?