The trailer for Oliver Stone?s thriller Snowden is out. The flick stars Joseph Gordon-Levitt as the NSA whistleblower Edward Snowden. It follows Snowden?s journey from the army to the CIA and then his resulting infamy as he leaked classified information about global surveillance. The film is based on The Snowden Files by the Guardian?s Luke Harding and Time of the Octopus by Anatoly Kucherena.