Chung Kuo is primarily set 200 years in the future in mile-high, continent-spanning cities made of a super-plastic called ‘ice’. Housing a global population of 40 billion, the cities are divided into 300 levels and success and prestige is measured by how far above the ground one lives. Some – in the Above – live in great comfort. Others – in the Lowers – live in squalor, whilst at the bottom of the pile is ‘Below the Net’, a place where the criminal element is exiled and left to rot. Beneath the cities lie the ruins of old Earth – the Clay – a lightless, stygian hell in which, astonishingly, humans still exist. These divisions are known as 'the world of levels'.