WikiLeaks founder Julian Assange and his colleague Daniel Domscheit-Berg team up to become underground watchdogs of the very powerful. They create a platform that allows whistleblowers to anonymously leak covert data. But when Assange and Berg gain access to the biggest trove of confidential intelligence documents in U.S. history, they battle each other and a defining question of our time: what are the costs of keeping secrets in a free society, and...