In their quest to gain control of the Solar System, the Daleks have taken possession of the Time Destructor, a weapon which threatens the safety of all who stand in their way. As they head up an alliance of alien races bent on destroying the human race, in their midst is none other than the treacherous Guardian of the Solar System, Mavic Chen.A dangerous chase ensues across volcanoes, jungles, deserts and futuristic cities, as the Doctor and his companions struggle to prevent the Daleks' plans coming to fruition. The stakes are high, and for the first time in the programme's history the lives of two TARDIS travellers are lost...