"Citizenfour" is anchored around an archetypal movie moment: journalists hold clandestine hotel room meetings with a source who divulges significant details about governmental corruption while simultaneously taking significant steps to make sure that they're not being monitored.

He disconnects the room phone; he panics over a sudden fire alarm; he covers himself in his shirt, just in case; he goes undercover by shaving and putting gel in his hair.

It all feels like tense fiction, of course, but in this case, it couldn't be more real. This documentary, from Laura Poitras, chronicles her initial meetings with NSA whistleblower Edward Snowden in a Hong Kong suite, alongside journalists Glenn Greenwald and Ewen McAskill.

No matter how you feel about Snowden and his decision to expose the agency's monumental global surveillance programs, there's no way to deny the fact that this is gripping, edge-of-your-seat stuff, offering the chance to experience a defining historical moment from the front lines.

Poitras gives the appropriate context to the Snowden meetings, but she structures the film like a classical thriller, complete with encrypted emails unfolding onscreen that spur considerable dramatic build-up to that first hotel summit.

The movie turns the familiar narrative inside-out; Poitras is an enormously perceptive filmmaker and she understands that this is a character study first. Some of the most crucial moments in the picture involve little more than close-ups on Snowden's face while watching the initial news broadcasts about his leak or learning, for the first time, of the fall-out for his girlfriend in Hawaii.

"Citizenfour" lands its gut punch there; the experience of watching the disclosures up-close-and-personal is compelling but the deeper considerations here, the question of what it takes to give up everything for a cause, even a controversial one, rarely has been more eloquently conveyed.

3.5 stars
Documentary by Laura Poitras
Rated R
Playing at IFC Center, Lincoln Plaza Cinemas