Featuring Edward Snowden and Glenn Greenwald. In English, Portuguese, and German, with English subtitles. Rated PG.

The various government and corporate interests tracking where you go, whom you meet, what you read, and what you ate for lunch don’t actually care about your opinions. But they do hope you at least passively join smear campaigns against people, like Edward Snowden, who represent threats, real or imagined, to their hegemony.

Demonizing whistleblowers like Snowden or Julian Assange, who also appears briefly in this tense, in-the-moment documentary, is just part of the story. The political wind-chill factor keeps dropping when we look at everything that has (and has not) happened since filmmaker Laura Poitras sat down in a Hong Kong courtroom with Snowden, journalist Glenn Greenwald, and another investigator from Greenwald’s English employer, the Guardian.

Poitras, who had previously made films critical of the so-called War on Terror—and suffered more than 40 interrogations at border crossings because of it—knew Snowden only as Citizenfour when he contacted her through encrypted emails. Her savvy was a central reason Snowden trusted her to capture the handover of incendiary documents to the Guardian. Like her subjects, Poitras has had to move abroad to protect her material from Uncle Sam’s reach, and she also travels to Brazil and other countries to follow the story.

Unlike Assange, Snowden wanted his documents interpreted for the most serious implications, rather than just releasing them en masse, with potential national-security consequences. It comes across forcefully in this must-see movie that the senior NSA analyst (then only 29) actually cared about such things. And his super-articulate rationales, while occasionally self-serving, make a convincing case for the decision to reveal systematic privacy invasions that go far beyond tapping into Verizon accounts and studying your Amazon purchases.

By film’s end, during which Chinese human-rights lawyers and UN officials figure out how to get him out of Hong Kong, you begin to wonder how long the guy will be allowed to live. For now, Russia, where he was stuck when Washington revoked his passport, has extended his temporary residence. Oh, and Oliver Stone is planning a feature with Joseph Gordon-Levitt as the edgy whistleblower. Even when a guy tries to act on principle, it still ends up being about his personality.