Mesopotamia — the cradle of civilisation. In the fertile crescent of land on the banks of the rivers Tigris and Euphrates, mankind is turning from hunter gatherer into farmer, and from farmer into city-dweller. Gilgamesh, the first hero-king, rules the city of Uruk. An equally legendary figure arrives, in a police telephone box: the TARDIS has brought the Doctor and his companion Ace to witness the first steps of mankind's long progress to the stars.