Michael Sheen and Maria Bello give brave performances as a married couple trying to come to terms with the quite incomprehensible. They shared a family home, yet found words increasingly hard to come by. Every strained dinner conversation was another reminder of the extent to which they’d used their son as a panacea; once hoping that a life of recitals and college tuition might somehow bridge the void. Now they seemed more like middle-aged strangers than partners, bound by a child they barely heard from. Vacations first postponed, then cancelled. Messages left were seldom returned, and even those that were took the form of vacuous pleasantries. Family, like marriage, becomes just another routine when you stop asking anything of one another, and how sad it is that it took their son killing himself and his classmates to remind them of that.

Films can be so focused on the event that they forget to consider what happens afterwards. Beautiful Boy exists almost entirely in that forgotten space, so much so that our only glimpses of the son are in a phone call on the eve of his death. Had his parents thought to truly listen, they might have sensed his growing preoccupation. They did not; there would always be tomorrow. Bill (Sheen) cut him short in favour of the evening paper, just as his mother (Bello) could think only to remind him to study hard and stay in school. Such words, imparting neither love nor warmth, are unlikely to have been those she’d have chosen with prescience, but then life always did have a way with irony.

By choosing to look beyond their tortured son, the film imagines instead what two perfect strangers might do when faced with the truth. Within minutes of the police making the announcement, a sea of reporters and cameras arrived to camp out on their lawn. The couple hide upstairs in the darkness of their son’s bedroom, finding stories and artefacts, but few explanations. How could they? Senseless acts are both more than the sum of their parts and, inversely, nothing at all. As parents, it must have been maddening to try and reason with that, no less so for it having been committed by a child they must now accept they hardly even knew.

Before long, they go to stay with Kate’s brother, who has a young family of his own and accommodates them as best he can. Bill quickly retreats to the comforting routines of work, only to find his presence there drawing the stares of co-workers who mistake judgement for concern. His wife, increasingly adrift, grows dependant on mothering her nephew. The fairytales that once delighted her own son are now gifted to him, in bedtime rituals that try to make sense of where she might have gone wrong. Late one night, as they dissect their roles, the hand-held camera draws in closer. Bill snaps. “I wish to god we hadn’t had him” he rages, throwing his wife to the floor. “I wish we hadn’t fucking had him”.

There are brief moments of relief. The couple break into unbridled laughter in a dinky motel room, meeting over cheap vending-machine snacks that kindle some forgotten passion. In all other respects, this remains a bleak and understated film, as arguably it must. There’s always the risk that drawing too much drama from a tragedy can leave it a silly artifice of grief, and Shawn Ku directs accordingly, with caution that leans on silence over words. Just about everything he wishes to convey can be found in the motionless prayers of a father, or a wife’s resentment that seems to extinguish all hope of redemption. To lose a child is to ask questions that cannot hope to yield answers, and Beautiful Boy must content itself with documenting the cogs’ futile spin.

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.