There’s an earnestness to Karen Moncrieff’s debut feature that’s not unlike what one would expect in a Lifetime telefilm, and the plot, focusing on domestic distress, echoes the network soap operas on which both the writer-director and the star appeared in the past: the basic trajectory (especially a turn it takes toward the close) is very familiar. But “Blue Car” nonetheless carries considerable punch; like last year’s “Swimming,” it’s one of the rare female coming-of-age stories in which the overall sense of authenticity more than compensates for the narrative lapses. When compared to a studio effort to mine similar territory (like “White Oleander,” for example), its sensitivity and honesty are all the more impressive.

Agnes Bruckner plays Meg, a teen who lives with her mother Diane (Margaret Colin) and younger sister Lily (Regan Arnold). She and her sibling are haunted by the departure of their father, and Diane’s desperate, apparently hopeless efforts to better herself place a great deal of the household burdens on her. Neither she nor her mother can really deal with the withdrawn Lily, whose pain and longing for a restored family are palpable, but Meg experiences some relief by writing poetry in a class presided over by the demanding but supportive Mr. Auster (David Strathairn); her verse is colored by the image of the car in which her dad departed. The crux of the plot comes when Meg, under Auster’s increasingly close direction, wins a local poetry contest that offers her the opportunity to go to a national competition in Florida. Her effort to get there will prove tumultuous, however, and domestic tragedy will intervene as well. The film closes with her trip south, during which her relationship with Auster veers in a direction that’s all too predictable. But it’s handled in a fashion more subdued that usual; thanks to the nuances that Bruckner and Strathairn bring to the material, even the inevitable public confrontation between the characters carries conviction.

It’s the treatment, in fact, that rescues “Blue Car” as a whole from the dangers of bathos and mawkishness. On the one hand, Moncrieff handles episodes that could easily have gone terribly awry with a delicate touch; in less assured hands, for example, the culmination of Lily’s depression might have been crudely embarrassing. But her skill is matched by the acting. Bruckner delivers a performance that seems way beyond her years; she captures both Meg’s strength and her vulnerability unerringly. Strathairn is equally fine, etching a portrait of a man who sees in his student a promise he himself never fulfilled—and whose weakness of character ultimately reveals itself. Colin and Arnold deliver strong support. Only Frances Fisher, as Auster’s brittle, alcoholic wife, strikes too melodramatic a note. The technical side of the film is simple and straightforward, which has the benefit of keeping attention on the actors—where it belongs.

“Blue Car” is the sort of screenplay that could easily have invited a crude, heavy-handed approach. But thanks to Moncrieff’s sensitivity and her outstanding cast, it transcends its roots and emerges as a touching, incisive portrait of a young girl whose potential is threatened by the accident of her birth and the problems of her parents.