Lean and relentless, patient and pitiless, “Killing Ground” is the sort of thriller that gives horror movies a good name.

It’s a reminder that the scariest things we see on the screen aren’t necessarily supernatural — they’re dangers we face from the human predators among us.

It’s an Australian version of the “Camping Trip to Hell” genre. A young couple (Harriet Dyer, Ian Meadows) head into the wilds of New South Wales to set up a tent near Gungilee Falls.

Fans of this genre will recognize the conventions — the “no cell service,” guy fumbling with a folding map (practically unheard of in the digital age), the stop at a convenience store where they encounter…THE THREAT.

That would be German, played by Aaron Pedersen, born to be a heavy. Bearded, glowering, with a gun-racked pick-up and a menacing pit bull caged in back, he suggests Ian and Sam go somewhere other than the falls, as their Mazda 3 lacks 4 wheel drive.

German, of course, has a running mate, a homely, sniggering creep (Aaron Glenane) who loves guns and the woods as much as he does.

There’s another car and tent at Sam and Ian’s preferred riverside beach. A family of four is there. No worries, plenty of room.

But the creeps, we’ve seen, have marked the teenage girl (Tiarnie Coupland) in that clan, pushing a stroller with her toddler/brother in it.

Then writer-director Damien Peters breaks formula in increasingly surprising and merciless ways. Time isn’t linear. We’re seeing two separate events. Something bad happened here, and something worse is about to.

Peters don’t pussyfoot around with his foreshadowing. We see a cell phone kept as a souvenir and destroyed “because what happens in the woods STAYS in the woods.”

Ian, we learn, is a doctor, and takes the time to explain the various tools on the Swiss Army knife he gives to Sam. And Sam? She’s the one who proposes to Ian.

Peters takes his time setting everything up, feeds us a diet of dread and then hits us with a genuinely hair-raising image — the couple, walking back to their car, concerned about what might be happening, and in the background, the toddler following them and toppling to the ground.

Suspense rises with each excruciating fork in the story’s path, each brutal encounter with rural rubes with guns. Peters loses points for the formula, mercilessly mocked in “Tucker & Dale Vs. Evil,” and with every banal “It’ll be OK” bit of dialogue, but gains points back with with every sinister variation he slaps into it.

After “A Cry in the Dark,” you’d think Aussies would be leery of packing a tent off into the bush. “Killing Ground” should remind them, and us, that there are greater dangers than dingoes eating your baby.

MPAA Rating:  unrated, with graphic violence, sexual assault

Cast: Harriet Dyer, Ian Meadows, Maya Stange, Aaron Pedersen, Aaron Glenane

Credits:Written and directed by Damien Power. An IFC Midnight release.

Running time: 1:30