In his third book, David Kilcullen takes us out of the mountains: away from the remote, rural guerrilla warfare of Afghanistan, and into the marginalised slums and complex security threats of the world’s coastal cities, where almost 75 per cent of us will be living by mid-century.Scrutinising major trends – population growth, coastal urbanisation, and increasing digital connectivity – he projects a future of feral cities and urban systems under stress, as well as greater overlaps between crime and war, internal and external threats, and the real and virtual worlds. Informed by Kilcullen’s own fieldwork in the Caribbean, Somalia, Afghanistan, and India, and that of his field-research team in cities in Central America and Africa, Out of the Mountains presents detailed, on-the-ground accounts of the new faces of modern conflict – from the 2008 Mumbai terrorist attacks, to transnational drug networks, local street gangs, and the uprisings of the Arab Spring. Deeply researched and compellingly argued, it is an invaluable roadmap to the future and its potential dangers.