SUPPOSEDLY, an Old West mountain man is listening to a recently arrived civilian describing the Apaches: "They don't know the difference between right and wrong!" The Westerner replies, "Why don't you wrong one and see what happens." That story comes to mind when watching the tense Aussie noir Animal Kingdom by David Michod.

The main character here is the soft-headed, morally childlike J (James Frecheville)—a hulking sad sack with a dim constellation of acne around his downturned, too-small mouth. His mom dies of a heroine overdose, and he's taken into the scary embrace of his Ma Barkerish grandmother (the incredible Jacki Weaver) and her brood of career criminals.

J ends up caught in the war between the crooked Melbourne drug squad and the family. Casualties are mounting. One soldier in this fight is a police detective (Guy Pearce) of uncertain honesty. The nightmarish Ben Mendelsohn is the clan's mastermind, referred to as "Pope."

Despite its undeniable force and often sensational acting, Animal Kingdom doesn't really snap together. The pace is erratic, and it seems more so because of Michod's choice of emphasis–what he includes and what he deletes.

If there's one thing most modern Australian films have in common it's a haze: a dreaminess, in which the harsh edges blur. It's like the 1970s never ended there. The everyday critic proposes it's the sun-blasted quality of Australia that filmmakers are trying to capture. That's probably too easy, and it won't wash because Animal Kingdom is set in Melbourne, a colder city. And there's only one sequence that's specifically out of the ring of suburbs, sinister motels and courtrooms. That sequence takes place when a wanted criminal makes a hopeless attempt to run out into the bush. Then the camera goes wide and shows us a traditional sunburnt Australian wide-open space, with no cover except for a couple of wide-apart trees.

But here, when key characters make a turn from passive to active, you don't feel completely prepared, even if the surprise works. You can sometimes feel left hung out to dry in mid-scene. Nevertheless, Animal Kingdom is an impressive thriller. The finale is a shocker. And if the movie raises more questions than it answers, it resolves the story of J with explosive emphasis. He's a grown-up animal at last.

ANIMAL KINGDOM (R; 120 min.), directed by David Michod and starring Guy Pearce, Jacki Weaver and James Frecheville, opens Friday at the Nickelodeon.

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