“Gimme Shelter,” a drama about a pregnant teen trapped in a home with her abusive mother, overcomes its mediocre production values by telling a simple, moving story.

Vanessa Hudgens, famous for her role as nice girl Gabriella Montez in Disney’s “High School Musical” movies, plays quite a different role as Agnes “Apple” Bailey, a troubled girl seeking safety she’s never had.

The former teen star is more than unrecognizable as the volatile Apple. She resembles one of the zombies in “The Walking Dead.” Likewise her out-of-control mom, June (Rosario Dawson).

When we meet Apple, as she prefers to be called, she’s in a state of rage. Ending up on the street, she’s a time bomb and her own worst enemy. A life less dangerous seems unlikely for her.

After Apple makes a violent break from her mother’s custody, her attempt to reconnect with the father she’s never known goes badly.

Writer-director Ronald Krauss based “Gimme Shelter” on real events. The facts of the story include a Wall Street executive whose daughter lived as a shelter resident.

Brendan Fraser, another of the movie’s well-known cast members, co-stars as Tom Fitzpatrick, Apple’s well-to-do dad. When Fraser isn’t perhaps underestimating this low-budget drama, he rises to the occasion.

Some early scenes feature Fitzpatrick and his long-lost daughter at his mansion home, with the woman Fitzpatrick married and the children he had years after he knew Apple’s mother. Apple’s abrupt appearance at her father’s door creates understandable friction.

“She smells and she’s weird,” Fitzpatrick’s young son says.

These introductory scenes are rocky. The director’s rhythm and tone are off. But the film and its cast grow more sure-footed as the story progresses.

A disaster leads to a potentially happier path for Apple after she steals a car and crashes it. Father Frank McCarthy, a Catholic priest played by another of the film’s famous faces (not to mention voices), James Earl Jones, introduces himself to this girl at the precipice. Predictably, Apple rejects his kindness.

“I don’t need a priest,” she says. “God don’t care about me!”

Krauss’ script needed smoothing. His transitions are rough and worse, implausible. For instance, Apple, having been such a lioness, soon goes lamblike to the priest. An earnest but amateurish development.

Krauss does intimacy and revelation better than conflict. He stages his quieter scenes with care. When one resident of a shelter for pregnant teens, for example, holds her newborn for the first time, tissues will be useful.

Predictable plot turns and a substandard soundtrack undermine the good in the film’s second and third acts, but “Gimme Shelter,” on balance, redeems itself. It becomes a poignant story of hope rising from darkness.