Doug Saunders’s important new book, Arrival City, deals with an unglamorous but bitingly important issue: the largest ever human migration. This is set to happen within most of our lifetimes. In 2008, for the first time, a majority of the world’s population lived in cities. According to the UN, the globe’s rural population will begin to decline in absolute terms within a decade, but its urban total will double from 3.4 to 6.4 billion between now and 2050. In short, mass urbanisation of the Third World is on its way. While various academic titles have plumbed this phenomenon, no single book – until now – has breathed such life and human drama into it. Free from the impressionistic exaggerations of Robert Kaplan or the flights of fancy of Mike Davis, the book engages while remaining serious. It pulls in the reader by centring its storyline on the fate of its numerous lead characters.