In Citizenfour you see Edward Snowden put a blanket over his head while typing in a password. He checks is a phone plugged out when he hears a fire alarm being tested saying how any modern phone can be turned into a listening device. But he is not a paranoid young man reading sensationalist articles on the internet. He was part of the NSA’s system that does the spying.

The film is the third part of Laura Poitras’ trilogy into American power’s choices post-9/11 and is undercut with a score straight out of a science-fiction dystopia. The film explains how there are 1.2million people on US government watch lists. How they can listen in to practically any communications in the world. It even shows the files they have on Poitras.

The bulk of the film is about Snowden in the days before, during and after his leaks. We get the most detailed insight into the days he spent in a Hong Kong hotel room with Poitras and other journalists Glenn Greenwald and Ewan MacAskil handing over the NSA files.

In her previous two films, Poitras is rarely seen and you don’t see much of her in this either. While this was ideal in those films I would’ve liked to have seen more of her this time around. Her other films followed other people and their stories but she was big part of this story. It’s not her style to stand in the limelight, but it would have been good to hear what happened to her after the story broke and her thoughts on it. Instead she focuses on Snowden and Greenwald.

She does well to give the film an ominous feeling without being sensationalist. Towards the end there is a night time shot looking in Snowden’s window as he cooks dinner with his girlfriend. It looks like it is an assassin staring in at them.

It’s a film that’ll be watched by people in years to come when they want to know what happened during those days. You won’t be in a good mood afterwards but it’s a gripping watch.

Citizenfour is now showing in the Irish Film Institute and Lighthouse Cinema in Dublin. It opens in the Triskel Arts Centre in Cork on December 7 and Queen’s Film Theatre in Belfast on December 13.