It all started with an unsigned email: "I am a senior officer in the intelligence community." What followed was the most stunning leak of classified information in history, the work of an unusual man. The consequences shook leaders worldwide, from Obama and Cameron to the presidents of Brazil, France, and Indonesia, and the chancellor of Germany.

Edward Snowden, a young IT whiz working at the National Security Agency of the United States, revealed how this powerful agency uses new technologies to spy on the entire planet. Spies refer to it as "domination of the internet." Others call it the death of our privacy.

This is the true story of Snowden's actions and the journalists who faced pressure from the governments of the U.S. and the UK to bury this remarkable scoop. Snowden's story reads like a thriller unfolding on a global scale, starting from the day he left his stunning girlfriend in Hawaii carrying four laptops full of secrets, to the weeks of leaking information in Hong Kong and his struggle for political asylum.

Now trapped in Moscow, a unique victim, he faces charges of espionage in the U.S., as well as an uncertain future in exile. What led Snowden to make this sacrifice? Award-winning Guardian journalist Luke Harding answers the question that should concern every citizen of the digital age.