We see the threat long before she does.

But Margo “Maggie” Crane (Kenadi DelaCerna) is 15, growing up without a mother in the pre-Internet 1970s of Northern Michigan. Her Native American Dad (Tatanka Means) taught her how to work the river, fish and hunt. He never warned her about the uncle next door.

And Margo, after taking the “Wanna go huntin’ with me?” bait, doesn’t recoil at Uncle Cal’s (Coburn Goss) sexual aggression. She leans into it. Curious? Flattered? Turned on?

The fury this act rains down on him — from her dad, Cal’s brother-in-law, and Cal’s enraged family doesn’t seem to register with the teenager. Until she breaks out her Winchester .22 and shoots Cal, escalating matters in ways she could never foresee.

“Once Upon a River” is a drab, downbeat indie period piece built on impulsive, stupid decisions and irrational and emotionally unmotivated reactions to their consequences.

The shooting that upends Margo’s life doesn’t tear her up in ways we can see. She’s got a gun and backwoods skills, access to a rowboat and a mother who ran out on her years before she can try to track down. She can take to the woods. The guilt, fear and anger we might see in a more interesting performance simply isn’t in DelaCerna’s tool kit.

The coming-of-age-on-the-lam story swims or sinks on her performance and every limp plot contrivance musician-turned-writer-director Harloua Rose throws in Margo’s path. And there’s a whole lot of sinking going on.

Rose keeps the look late-fall and wintry and the tone dour, with little moments of magical plot-engineering that promise to house and feed our heroine whenever the chips are down.

She lays low with “safe” friends of her father, meets a sensitive hunky Native writer/adventurer (Ajuawak Kapashesit) just when she needs to, a dying, kindly old coot (John Ashton) at the perfect moment, and even her mom (“True Blood’s” Lindsay Pulsipher, the stand-out in the cast) promises to solve every grim 15 year-old problem her daughter finds herself facing.

We see her dressing wildlife she’s going to eat. But this “camping” she’s doing? The survivalist/live-by-your-wits part of the tale is shortchanged.

DelaCerna’s take on Maggie is timid, as meek and passive as the “pip pip” of her .22, which she brings down deer with. Hey, it’s a movie.

And that rape scene is…seriously 1977 and problematic. Did I mention she’s 15?

The basic ingredients of something gripping, tense and heartfelt, and in an unusual setting and culture, are here. Our director/cook spoiled the stew, with a lot of help from her miscast-cast main ingredient.

MPAA Rating: unrated, rape, gun violence, alcohol abuse

Cast: Kenadi DelaCerna, John Ashton, Tatanka Means, Coburn Goss, Sam Straley, Kenn E. Head and Lindsay Pulsipher

Credits: Written and directed by Haroula Rose, based on a book by Bonnie Jo Campbell. A Film Movement release.

Running time: 1:32