Like it or not, and chances are you'll feel both ends of the emotional pendulum before this astounding documentary is over, The Gatekeepers is an important film. Dror Moreh speaks with six former heads of Israel's Shin Bet, the agency charged with national security, men whose work is a closely guarded state secret. Agree or disagree, their views about the occupation of Gaza and the West Bank, and the political landscape that shaped their work, is essential viewing for anyone concerned about the future of the Middle East.

That Moreh was able to speak with any of them at all is remarkable in itself, none have agreed to interviews before. Yet he speaks with the entire leadership from 1981 to 2011 which accounts for thirty years of occupation, two intifadas and the assassination of a prime minister. Yet its not access that makes this documentary so surprising, its how the debut director coaxes such honesty from his formidable subjects that is astounding, particularly as they paint a startling portrait of disaster. Not surprisingly, The Gatekeepers earned Moreh an Oscar nomination for Best Documentary.

Given the film's audience's inevitable and strident preconceptions, Moreh's talent likes in an ability to keep us into the room with open ears. Not that he gives an easy ride – one moment you're nodding, the next you're squirming with anger before then reevaluating what just minutes earlier had seemed an unshakable truth. Most surprising is the revelation of a collective view by Shin Bet's leaders who believe that the hope they fought so hard to hold on to seems further away than ever. That radical settlers, extremist Rabbi's and the politicians who enable them have made what was once possible, impossible. And that each successive leader of Shin Bet has made a great problem greater. It amounts to an admission of failure from powerful officials whose guiding purpose has been to keep the nation safe. It's powerful stuff.

// COLIN FRASER

Previewed at Sony Theatrette, Sydney, on 8 July 2013