Female film directors are such rare creatures in Hollywood, and so it’s always a delight to find a new one with such talent and such promise as Kristen Sheridan displays in her tender, enchanting August Rush, an urban fable of family lost and gifts found... and refound. Sheridan may have had a bit of an unfair advantage when it comes to directing: Her father is Jim Sheridan, whose films such as My Left Foot and In America (for which Kristen shared an Oscar nomination with her father and sister, Naomi, for Best Original Screenplay) burst with a passionate humanism that celebrates individual potential and capability. Now it’s clear that Kristen has inherited some of that spirit, for this is a joyful movie -- so joyful, in fact, that its soul and heart triumph over the many flaws of some of its separate parts.

Though it’s easy, perhaps, to dismiss or accept or forgive those flaws if you take August as it is intended: as a modern fairy tale. If you can suspend your disbelief and overlook the deep implausibility of the story it’s telling, it becomes all too easy to embrace it. Evan Taylor is an 11-year-old little boy lost, and yet supremely centered with it: Stuck in an orphanage where he is derided by the other boys as a “freak,” he refuses to relinquish his firmly held belief that his parents want him, that maybe they’re just lost and haven’t been able to find him. Though he has never touched a musical instrument, he lives and breathes music, hears it “in the air, in the light,” in everything all around him. He believes the music connects him to his absent parents, and that through the music, he will one day find them. And then he decides not to wait, but to set out to find them himself, an odyssey that draws him to New York City, and all the strange dark magic of that 21st-century Oz.

Among the several enthralling things about August is how Sheridan (whose first feature film, 2001’s Disco Pigs, was an independent European production that was not released in the United States, though copies of the out-of-print DVD are available) captures the symphony of the city that Evan hears in his head: the rhythm and the groove of rattling subway trains and honking taxi horns and surging mobs of pedestrians and even plastic bags whipped by a breeze. Her depiction of New York might be the loveliest I’ve ever seen on film, a visually and aurally melodic valentine to the hustle and bustle and clamor.

But none of that would have mattered if she hadn’t found the right young actor to play Evan, for the movie rests on that character’s slender and sensitive shoulders. This is one of the more demanding child roles in recent memory, one made even more challenging by circumstance -- Sheridan cast Freddie Highmore (Arthur and the Invisibles, Charlie and the Chocolate Factory) precisely for the very reason I first noticed him, too: because he was able to go head-to-head with Johnny Depp, and hold his own in the process, in that lovely scene on the park bench toward the end of Finding Neverland. But Highmore is English, and Evan is American... and yet the actor, 14 when the film was shot last year, pulls off not just the accent -- astonishingly -- but Evan as well, with all his off-kilter confidence and preadolescent artlessness and supreme joy in the music only he hears. Highmore is a wonder.

The rest of the cast hits that perfect middle ground between magic and groundedness, too. Keri Russell (Waitress, Mission: Impossible III) and Jonathan Rhys Meyers (Alexander, Vanity Fair) as Evan’s parents share their own interrupted love story that is like something out of Cinderella gone 21st century: they’re both musicians themselves, and after a single romantic night at the ball they lose track of more than each other; they lose their music, too. They find it again, of course, as they must also find the son they never knew they had (how Mom could not know she has a child is one of those nagging implausibilities, but go with it), which becomes a gentle yet dynamic ode to the power of love and of family. And that necessary bit of fairy-tale menace comes via Robin Williams (License to Wed, Night at the Museum) as a Fagin-like presence in Evan’s life, the spirit-guide who first recognizes Evan’s talent (and gives him the nom de musique “August Rush”) and, simultaneously, the threat who endangers the full expression of that talent.

Is it all ridiculously improbable? Sure it is. But so is Cinderella, and Oliver Twist, and all the fairy tales we love. They turn out pretty satisfying in the end anyway, and so this one does, too.