In this era of zombie apocalypse mania, werewolves have been shunted off to the side, but Fritz Bohm’s feature debut offers an intriguing spin on the hairy (and, one might add, hoary) old genre, except in this case the creature is called a wildling.

What precisely is a wildling? The term is explained in considerable detail by a character called Daddy (Brad Dourif) in the film’s first act, as he tells horrifying bedtime stories to a young girl named Anna (played first by Arlo Mertz and then by Aviva Winick). The wildling, he says, is a hairy beast with sharp teeth, with which it devours children. That, he explains, is why he keeps Anna in her drab, dark room with the doorknob rigged to deliver an electric shock if she attempts to leave.

But that’s not all Daddy is doing to Anna. No, he’s not a pedophile, but he is treating her with painful injections (delivered to the stomach), which he claims are medicinal but instead seem designed to obstruct the maturation process. So while she grows externally into a young woman (Bel Powley), she remains childlike in other physical respects.

When the drugs prove not to be working, however, Daddy takes an apparently drastic action that sends Anna into the outside world. After a hospital stay, she is taken in by Sheriff Ellen Cooper (Liv Tyler), a kindly sort who thinks she requires more personal treatment than a regular foster home would provide. There Anna begins to learn about ordinary life, not only from Ellen but from her younger brother Ray (Collin Kelly-Sordelet). Though he’s bullied at school, he tries to protect her against the class thugs, and they grow closer over time.

But Anna is undergoing some profound changes—not just puberty but something quite unusual. You have probably already guessed what that is, but if not her gradual transformation toward wildness and the encounters she has with a man decked out in wolfskins (James Le Gros) during her rambles through the forest should make matters clear. By the time a confrontation with one of the school bullies after a teen party goes completely awry, it has become obvious what Anna is becoming, and why Daddy was so intent on preventing it from happening. The outcome sends Anna and Ray fleeing into the woods to escape a gang of hunters aiming to end the problem before it escalates further; it’s led by a familiar face.

On one level, “Wildling” is a parable of woman’s coming of age, a metaphor of female empowerment. But it’s also a genre piece, a revisionist take on the werewolf legend that strips it of the oft-repeated tropes about silver bullets and the full moon and offers a different mythology to replace it, one based on evolutionary principles that might be no less absurd but at least makes it different.

And Bohm, his co-writer Florian Eder, and their collaborators—cinematographer Toby Oliver, production designer Lauren Fitzsimmons, editors Robb and Matthew Sullivan and composer Paul Haslinger—have put together a package that works surprisingly well for an hour or so, building a feeling of dread that’s made palpable by Powley’s stunning performance and sympathetic support from Kelly-Sordelet. (One might question whether even so lonesome a kid as Ray would be drawn to the increasingly formidable Anna to the extent that he is, but Kelly-Sordelet exudes enough vulnerability to make it plausible.)

By contrast Dourif comes across as creepy, but in a rather familiar fashion, while Tyler’s restraint leaves Ellen seeming a bit dense, and Le Gros can’t do much with the oddball Wolf Man figure.

In the final half-hour, “Wildling” becomes something more conventional—a chase movie pitting the now-feral Anna against a mob that’s out to do her in—and the chase goes on rather too long for comfort.

But if it reaches the finish line a bit winded, Bohm’s movie, powered by Powley’s strong turn, should please genre fans looking for something different—old wine, perhaps, but in a spiffy new bottle.