The Snowtown Murders comes across as an unpleasant, distressing movie, which doesn’t mean it’s not a good one. Aided by noteworthy sound and photography in his first feature, film and theater designer Justin Kurzel hails from near where the grisly events took place and captures the obscene yet banal quality of vigilantism co-opted and gone gruesome. A cast of mostly local, mostly first-time film actors is chillingly convincing.

Drawbacks there are. “Specific to their world,” the Aussie accents are thick and hard to decipher. Who’s who and why’s why are not always clear, and some relationships remain obscure in Faulknerian insistence on life’s unknowability, with gaps filled in later or never. Time allotment could have been handled, not necessarily better but differently: little or no character background is furnished, while future consequences are hurried in via printed endnotes after exactly two hours of buildup, like a written line that runs out of page-space.

Some will view the theme as innocence perverted, while others might extend it to the psychopath’s hijacking of an entire nation-community like Germany under Hitler. Derived from two books on the 1992-99 events -- Killing for Pleasure and The Snowtown Murders -- Shaun Grant’s screenplay enters the story through Jamie (newcomer Lucas Pittaway, discovered in a shopping center), a teenager so traumatized and withdrawn that emotions are acted out but scarcely vocalized.

“Nature vs. Nurture,” born or bred, is elsewhere mentioned in connection with Jamie and, indeed, the entire community. While the Adelaide area of Snowtown is poor, welfare dependent and drug- and alcohol-addicted, what proves most mainstream surprising, or underpublicized, is not sex or violence per se but the amount of abuse of minors, homosexual, incestuous and otherwise.

That such a homogeneous community -- no minorities are shown -- -can be sweet-talked, cajoled or bamboozled into complicity or active participation in brutal “retaliation” is shocking although, again given nationalism of the last century, not all that unexpected. Not so much the publicized “organized group of serial killers” as their sometimes uneasy abettors, especially when their own fall under suspicion, the neighbors may not be unrepresentative, either.

Elizabeth Harvey (Louise Harris, found while out shopping) is single-parenting two adolescent sons and a nine-year-old, their father David (Beau Gosling) living nearby with older son Troy (Anthony Groves) and rebuffed in his desire to return. Her current man from across the street takes care of the house for a few hours, gets naked, and takes nude Polaroids of the boys. She throws him out, at once to find another boyfriend.

SPOILER ALERT

The bearded, twinkling, cherubic John Bunting (a first feature for TV and theater actor Daniel Henshall) seems a tolerant father figure who takes the kids out on his Honda and is too good to be true. Handy at repairs and cooking and presiding over utensil- and chewing-noise meals, he initiates Jamie into pederast payback with chopped-up kangaroos. He organizes block meetings, getting folks to feel at ease, discuss problems, and identify local deviants and other undesirables. By force of personality, he overcomes Jamie’s reluctance to shoot a pet dog at point-blank and, despite the boy’s revulsion, to dispose of a junkie friend’s body. From there, the boy is drawn into deeper implication in torturing and killing targeted others.

Contrary to claims of hero-worship obedience, it is more that Jamie is too emotionally unsure to resist and his distraught mother powerless to save them all. Blood scenes, human and animal, are not drawn out but are tough to watch even to forced cassette recordings. Fascist power hunger and theories of justified “cleansing” are hinted, but there is also near-erotic pleasure in nose-to-nose extermination.

The web spins wider, collusion deeper, not only for the boy but for all the psychological victims of Bunting’s bullying. The film story ends abruptly, a door closing on another imminent elimination of, notes say, the total of twelve.

What allowed for continuation and what finally exposed the perpetrators are not indicated, though their fates are related in print. The story on-screen is of the crimes themselves, with individual motivations falling outside those parameters. Justice is delayed, disembodied and told instead of seen, secondary to the central portrayal.

(Released by IFC Films; not rated by MPAA.)