CITIZENFOUR, Laura Poitras’s Oscar-winning documentary about the NSA whistleblower Edward Snowden, is a riveting watch from start to finish.

I love a really well-crafted documentary and CITIZENFOUR, Laura Poitras’s 2014 Oscar-winning film about the NSA whistleblower Edward Snowden, is a complete gem in this regard. It’s a documentary that completely blew me away when I first saw it. And it’s one I return to every now and then because it’s simply a riveting watch from start to finish.

Edward Snowden talks with Glenn Greenwald in Citizenfour

Edward Snowden talks with journalist Glenn Greenwald

In January 2013, the film-maker Laura Poitras started receiving anonymous encrypted emails from someone calling themselves “CITIZENFOUR”. The source said they had proof of the illegal covert surveillance that the NSA (National Security Agency) was undertaking on people across the world.

Five months later, Poitras found herself in Hong Kong along with independent journalist Glenn Greenwald and Ewen MacAskill of The Guardian to meet the source of the emails who was, of course, Edward Snowden. Over the next few days, the film-maker and the two journalists sat and listened – with Poitras recording – to Snowden’s information and were both sceptical and blown away. Could this rather paranoid young man really be divulging this incredibly sensitive and damning information and in the process, making a truly patriotic stand by risking everything to tell the world the truth?

It doesn’t matter if you think you know this story and who Edward Snowden is and why he did what he did, Poitras’s gripping film plays out like the best kind of thriller, where each scene builds the tension onto the last and the result unfolds in front of you with pure, understated power. It’s up there for me with those other extraordinary and Oscar-winning documentaries I’ve written about in this blog, Asif Kapadia’s Senna and Kevin Macdonald’s One Day in September. Like them, CITIZENFOUR is a movie that will stay with you for a very long time.