“Game of Thrones” has staked a major claim on the word “wildling,” but here it denotes a primal fairy tale of sorts. Bel Powley (“The Diary of a Teenage Girl”) is teenage Anna, rescued from a childhood in total isolation at the hands of a kidnapper (Brad Dourif). He called himself her father but wasn’t, and kept her on puberty-arresting drugs.

Sent to temporarily live with the kind police officer (Liv Tyler) who found her, she begins a transition into society that’s complicated by her own, increasingly strange hormonal progression — and her fear of “the Wildling,” the being that her quasi-father warned would try to steal her away.

A supernatural “What’s Happening to My Body?” parable in company with “Carrie,” “Ginger Snaps” and last year’s “Thelma,” “Wildling” is low-key with an undertone of menace, skillfully directed by Fritz Böhm in his feature debut (though some of his nighttime scenes are so dark it’s genuinely hard to tell what’s going on).

Powley uses her expressive face perfectly as the guileless Anna, coping with developments like body hair in strange places and an internal, rumbling snarl whenever she feels threatened. You know, teenage stuff.

But Böhm isn’t playing this quiet indie for laughs, and he’s got a solid supporting cast in Tyler, James Le Gros as an enigmatic mountain man, and Collin Kelly-Sordelet as the cop’s younger brother, who takes a shine to the unconventional Anna. Young love never goes smoothly, but the way this courtship plays out will likely surprise you.