Directed by first-time feature filmmaker Justin Kurzel, Snowtown is based on one of the worst serial killing chapters in Australian history — the infamous “bodies in the barrels” case in which the remains of 12 people were discovered in barrels of acid at a vacant high school in a South Australian town in 2003. The killers were found, arrested and sentenced, and the film depicts their lives leading up to their incarceration.

The initial and arguably most important challenge for Kurzel and screenwriter Shaun Grant, also a first-timer, was to decide how to approach the material. Would they humanise the villains, make the film a mission to depict them as more than monsters? Would they drench the experience in darkness and despair, shape it as meat-hook social realism, a portrait of suburban hell on earth? Or would they tread the Wolf Creek (2005) route and turn the events into a popcorn-and-Coke genre exercise, a midnight movie scare-fest marketed to squealers and thrill seekers?

Kurzel and Grant chose none of the above, though plenty of dark cross-genre elements invariably creep into the woodwork. Kurzel chose “to build the film from the inside out”, as he likes to say in interviews. In other words to make a close and immersing film in which the audience feel like they’re seated on crappy chairs around a Formica table cluttered with ash trays and empty stubbies as killer John Bunting (Daniel Henshall) explains which people in his community deserve to die. If so, mission accomplished.

Snowtown unfolds as one part social realism, one part kitchen-sink drama and one part thriller. The film has an airtight sense of verisimilitude maintained by unwavering directorial focus and an incredible cast. Amazingly, almost all of them are non-professional actors.

It’s engaging from the opening scene but the scariness is a slow burn, a gradual atmospheric intoxication that drifts into the viewer’s brain and central nervous system. It takes some time to realise just how toxic the air has become. That’s when the film moves into glimpses of r-pe and torture, the audience now dug in uncomfortably deep, controlled by the filmmakers who masterfully tread the line between what to show and what to keep in the shadows. Much of the violence is implied.

Snowtown isn’t just a brilliant piece of blood-curdling cinema; it isn’t just one of the best local features of this or any year. It is the most frightening Australian film ever made, and a great piece of art that stands on the same shelf as hard-hitting masterpieces such as Samson & Delilah (2009), Breaker Morant (1980) and Wake in Fright (1971).

The details: Snowtown opens in cinemas nationally today.