The end of Europe’s empires has so often been seen as a story of high politics and warfare. In Tim Harper’s remarkable new book the narrative is very different: it shows how empires were fundamentally undermined from below. Using the new technology of cheap printing presses, global travel and the widespread use of French and English, young radicals from across Asia were able to communicate in ways simply not available before. These clandestine networks stretched to the heart of the imperial metropolises: to London, to Paris, to the Americas, but also increasingly to Moscow. They created a secret global network which was for decades engaged in bitter fighting with imperial police forces. They gathered in the great cities of Asia and plotted the end of the colonial regimes with ceaseless ingenuity, both through persuasion and terrorism.