In 2012 the security journalist Glenn Greenwald received an email from Edward Snowden, a contractor for the National Security Agency. At a clandestine meeting in Hong Kong Snowden handed over flash drives detailing the scale of illegal spying by the USA and Britain. This bestselling book gives the inside story of what followed: the fear of discovery and arrest, Snowden's flight to Russia, and the attempts to cover up this massive abuse of power.