Here's Edward Snowden, Glenn Greenwald, and, offscreen, Poitras herself, holed up in a Hong Kong hotel room, plotting the revelation of the National Security Agency's spying on our phone calls, emails, Web searches, Amazon purchases, and everything else. Here's Snowden, the activist, conferring with Greenwald, the journalist, about how to make the story about Snowden's leaks rather than Snowden himself. And here's Poitras -- journalist and activist -- capturing their elation, their seriousness, their idealism, their spy-story jitters.
Trim and proud, given to stiff pontificating, Snowden relishes this seizing of history, just as Poitras's camera relishes him. But once Greenwald publishes his first Guardian story on Snowden's revelations, we see cracks in the whistleblower's principled serenity. Condemning yourself for a cause you know to be just is still condemning yourself, and by his last day in that hotel room, Snowden appears wan and harried, his face breaking out. Just watching, you might feel the same.
As in her previous films The Oath and My Country, My Country, Poitras is adept at illuminating multiple angles of complex, even prickly people. Here, though, she's a convert rather than a journalist, and she never bothers with some of the basics: The film takes as its given the NSA's perfidy and Snowden's heroism, offering little to persuade anyone unconvinced of either. Citizenfour marvels at what it could be probing.