“Beast of War” sets up as a fine if not wholly novel approach to the WWII combat “grunts” journey long before it settles into its true destiny — a shark attack tale.

Writer-director Kiah Roache-Turner trots through the tropes of boot camp, with its training, bullying, standing up to bullies, flirting with nurses and the like in a story that reminds us the Aussies took a back seat to almost no culture when it came to racism. We taste the experiences of an Aboriginal recruit (Mark Coles Smith) who is too competent, too big and too tough to take much guff off his tormentors.

Leo has been through things as a boy and survived. No “darkie” or “rock ape” insult from his better-paid white comrades (his training and combat pay is two thirds theirs) shakes his self-assuredness. He helps weaker Will (Joel Nankervis) through a jungle run, and when Will is picked on, Leo gets even on his behalf.

Nurses (Lauren Grimson, Lara Logan Browne) at the boot camp? Leo’s the one confident enough to flirt with them.

But we know a few things about what’s to come. It’s 1942, and boot camp doesn’t last long. They’ll be shipping out for the fight over Papua/New Guinea sooner rather than later. And our writer-director is known for horror — “Wyrmwood: Road of the Dead” and “Sting” were his.

It won’t be long before their troop ship is sunk in the Timor Sea, and Leo, Will, bully Des (Sam Delich) and others (Lee Tiger Halley, Sam Parnonson, Maximillian Johnson) are staring out into the dark fog of night in a sea of debris and corpses and somebody says that line somebody always says in a shark movie.

“What the Hell was that?“

Truth be told, that turn towards finned terror is a disappointment, seeing as how Roache-Turner cast this well and has an interesting angle for a combat film. There hasn’t been a movie about Aboriginal Austrlian soldiers jungle-fighting for King and racist country in WWII, near as I can tell.

Once the narrative shifts to surving that shipwreck, the small group friction and terrors of survival on floating debris, “Beast of War” becomes a simple “Who gets eaten next” and “How can we fight back/survive” tale, albeit one with a spiritual subtext as our young recruit knows sharks and experienced the trauma of an attack as a tween.

Mechanical/CGI shark attack simulations have improved over the decades, and are as terrifying as ever. But the longer this brief “inspired by true events” tale goes on, the more tropes and far-fetched cliches Roach-Turner trots out.

It’s a pity, because the generic story he begins with had more to offer the generic shark/horror tale he winds up telling.

Rating: R, graphic, gruesome violence

Cast: Mark Coles Smith, Joel Nankervis, Sam Delich, Lee Tiger Halley, Lauren Grimson, Sam Parnonson, Lara Logan Browne and Steve Le Marquand

Credits: Scripted and directed by Kiah Roache-Turner. A Well Go USA release.

Running time: 1:27