Film review: The Act of Killing (15)

Political exposé: Joshua Oppenheimer's documentary about the genocide in Indonesia, 'The Act of Killing'

In 1965, in the aftermath of a failed military coup, Indonesian death squads killed an estimated 500,000 "suspected communists".

This jaw-dropping documentary is about a collective state of denial that now exists within Indonesian society, and more specifically, about the rationalisations by which some of the men who did the actual killing have been able, not just to live with themselves but to prosper in positions of government and authority.

Its most extraordinary character is Anwar Congo, a gangster-turned-paramilitary leader thought to have personally garrotted around 1,000 people. He begins the film as a movie- and Elvis-obsessed old man cheerfully reminiscing about old times .

But as the result of an extraordinary act of psychological manipulation on the part of the film-makers, who encouraged the killers to make movies re-enacting their crimes, Congo's self-justifications begin to crumble.

The re-enactments become acts of remembrance, and the past is brought back to life as a surreal waking nightmare. An utterly fascinating, chilling, but important film.