Martha Jones secretly returns to England. Its been a year since the Master took over the Earth and launched the invasion. Humans are now a captive race and the Toclafane are building a fleet of rockets they will use to attack other worlds. The Master takes great pleasure in humiliating the Doctor and has Marthas family doing menial chores. Martha has a plan, however, and all she has to do is get in to see the Master. When she learns of the origin of the Toclafane, she realises the paradox they have created.