Between 1992 and 1999, a small Adelaide community were witness to a series of gruesome murders. Of the eleven people that died, eight were discovered in barrels, with the remaining three buried in shallow graves. Some of the victims were child molesters, while others committed crimes no more heinous than to be gay or, in one instance, merely handicapped. The events that led to their deaths are a lesson not just in the horrors of unchecked ideologies, but in how such horrors can find willing accomplices in desperate communities.

Jamie Vlassakis was a thoughtful young man when he was stripped and photographed by a neighbour, and no less so the day a family friend raped him on the living room floor. The camera observes these moments with little interest, the lone sound of the test match commentary on TV a signal that such brutality has somehow become normalised. It watches, too, the insidious arrival of John Bunting, whom we recognise now as one of Australia’s most depraved serial killers, but who seemed then if not exactly charismatic, then at least conducive to a greater good.

The ease with which Bunting emerged as a community leader is frightening in its verity. He was undoubtedly a child of history; all too aware of the power that comes from a commanding voice in bleak times. As depicted, he would call impromptu kitchen meetings for friends and neighbours, using the occasions to exploit an undercurrent of fear – fear that Snowtown was awash with paedophiles; fear the police were powerless to intervene. Manners and grace saw him quickly ingratiate himself with the Vlassakis family, whose eldest son he saw as possessing an enduring and particularly malleable innocence. It was Bunting himself who insisted Jamie sit in on his first meeting, in which he was encouraged to echo back the vitriol of the group. Later, he would faithfully execute Bunting’s own dog.

Here is a movie that takes an unflinching approach to barbarism. Cathartic revenge – the pair dumping rotting offal on the porch of a local voyeur – eventually gives way to a more brutal form of vigilantism, so aggressively unpleasant that at times I felt moved to step away. That isn’t something that could ever be said for the cartoon violence of The Human Centipede, a film that doesn’t even begin to equivocate with Bunting savagely torturing a man in a blood-smeared bathroom, only to repeatedly back off so as to extend his own pleasure. It is one of the most indescribably horrific scenes to be committed to film, made all the more unpalatable by Daniel Henshall’s intense, focused performance, and his depiction of a living, breathing monster.

The sad truth of Snowtown is that for every inhuman act, ordinary people stood quietly in support. Bunting and his associates may have acting out their fantasies alone, but they were not so when it came time to vilify the so-called ‘undesirables’ of the community, nor when Bunting advocated their executions to a baying crowd. More frightening still is that he was happy – and able – to confound genuine menace with his own misguided bigotry, coaching the bile in a language that will be familiar to anyone who has had the misfortune to observe a modern-day political lynch mob.

The enemy of my enemy is not a friend, and to watch Jamie, then just 16-years-old, being pulled into that world is to experience a profound sense of helplessness. The brave, the incendiary, the innocuous John Bunting was a Trojan horse for evil unbound, destroying a young life for little more than sadism and vengeful infamy.