The TARDIS lands in a London of future times - a city of fear, devastation and holocaust ... a city now ruled by Daleks. The Doctor and his companions meet a team of underground resistance workers, among the few survivors, but after an unsuccessful attack on the Dalek spaceship, they are all forced to flee the capital. A perilous journey through England finally brings them to the secret centre of Dalek operations ... and the mysterious reason for the Dalek invasion of Earth!