In early 2013, film director Laura Poitras begins receiving encrypted emails from a stranger who identifies himself as "Citizenfour." This anonymous source, later revealed to be Edward Snowden, claims to have evidence of covert and expansive surveillance programs conducted by the U.S. National Security Agency (NSA). Poitras, along with journalist Glenn Greenwald, arranges to meet Snowden in Hong Kong where they discuss the far-reaching implications of government surveillance on privacy and civil liberties. Over the course of several days, Snowden explains in detail how the NSA collects and monitors global communications without warrants, which includes data from private emails, phone calls, and internet activities of ordinary citizens.

As Snowden's materials are examined and verified, Poitras and Greenwald prepare to publish some of the most critical leaks in modern history. The intense atmosphere in the Hong Kong hotel room is palpable, filled with a sense of urgency as they anticipate the global reactions and personal consequences that will soon follow. The film expertly captures Snowden's principled decision to reveal these secrets despite the risks he faces. It highlights his unwavering belief in the public's right to know about government overreach and motivates a significant discussion on the balance between national security and individual privacy rights.