High above London and its crust of smog, stretched tall above the soapy atmosphere of the Earth, is a ship the size and exact shape of St Pancras railway station. On board, the Doctor and that mysterious lady adventurer, Iris Wildthyme, are bargaining for their lives with creatures determined to infiltrate the 1970s in the guise of characters from nineteenth-century novels. Without the help of UNIT, the Doctor and his friends face the daunting task of defeating aliens, marauding robot sheep, the mysterious Children of Destiny and... the being who calls himself Verdigris.