The Doctor and Ace are trying to enjoy a brief respite on Earth but they find themselves facing attacks both from the past and the present, all the while a looming threat approaches the planet.This week, Paddy and Tricia follow The Doctor and Ace as try to stop a militant group, an alien threat and a maniacal sorceress from gathering together the component of ancient Time Lord weapon. Will they be able find the pieces first or will Earth fall victim to the Silver Nemesis?