As the story goes, Jerry Mitchell, the Broadway choreographer, director and two-time Tony Award winner, picked up a copy of British author Terry Ronald’s “Becoming Nancy” at an airport a few years back. One brisk read, and he decided he’d found the perfect material for a new musical.

In Ronald’s 2011 coming-of-age novel, a high-school teacher in a working-class London suburb gets the genius idea of casting a boy as Nancy in the musical “Oliver!” David, a nerdy kid who adores Kate Bush, Debbie Harry and Sting, gets to put on a red dress and boa and play opposite the handsome football captain Maxie Boswell’s Bill.

But along the way, the exercise in cross-gender casting, circa 1979, goes horribly amok. Instead of being warmly embraced by their parents and peers, David; his best friend, Francis, a young black woman; and Maxie are attacked by a mob of racist, homophobic Neo-Nazis, and their production of “Oliver!” is nearly sabotaged.

Based on the world-premiere musical adaptation of “Becoming Nancy,” unveiled Wednesday night at the Alliance Theatre, maybe Mitchell should have left that novel at the airport.

As written by Elliot Davis (book), George Stiles (music) and Anthony Drewe (lyrics), and directed and choreographed by Mitchell, “Becoming Nancy” is a tonally jarring work that cloaks disturbing stereotypes and offensive language in a hyper-energetic swell of song-and-dance numbers before ending with an anthem of self-love called “You Matter.”

Maybe so.

But before David (Zachary Sayle), Maxie (Jake Boyd) and Francis (Jasmine Rogers) can embrace their inner beauty, they will be subjected to name-calling, violence and brutality that far surpasses acceptable school-boy shenanigans. (Parents, beware: The show is not recommended for audience members under 16.)

To be certain, “Becoming Nancy” is lavishly staged, peppered with likable songs, and distinguished by top-notch performances. Scenic designer David Rockwell creates a fabulous, fine-boned high-school gymnasium, sumptuously lit by Philip S. Rosenberg, and Amy Clark contributes costumes that are appropriate to the almost-’80s vibe.

Despite the weirdness of the material, the cast soldiers on, and sometimes soars.

Sayle exudes the kind of awkward, ugly-duckling persona that suits this urban fairy tale’s Cinderella-in-the-making. Boyd’s Maxie fits the mold of the handsome prince; he’s a Greek god chiseled in alabaster. The boys’ sexual awakening has some lovely and funny moments, as when David gasps at Maxie’s six-pack, but I don’t feel a genuine connection in this match. The truest character here is Rogers’ Francis, who maintains her dignity in the cruelest of circumstances (“My Skin”).

Jasmine Rogers as Gloria Gaynor, Jake Boyd as Maxie Boswell and Zachary Sayle as David Starr in “Becoming Nancy” at the Alliance Theater. Photo credit Greg Mooney

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These are the good kids. At the opposite end of the spectrum, Caleb Jensen’s Jason Lancaster and Seth Clayton’s Squirrel make for pretty convincing villains.

The conceit in which David’s posters of Bush (Jessica Vosk), Harry (Sally Ann Triplett) and Sting (Stephen Ashfield) come to life gets tired after a while. (For the record, Triplett, Vosk and Ashfield double as David’s mother, aunt and drama teacher, respectively.) And don’t get me started on the ABBA silliness.

Early on in “Becoming Nancy,” you start to sense that there are dark forces at play under the Disney-esque veneer. Is this “High School Musical,” or “Urinetown”? There’s something menacing about these mean kids, something sinister.

When David and Maxie get caught making out, their parents freak out. When the musical-theater kids decide to support a Rock Against Racism concert, they are attacked. Eventually, the perpetrators are unmasked. No shock who they are, but there is one surprising and unsettling twist. It all make Dickens look like a day the beach.

Art has always held up a mirror to the good and the bad of the human condition. Many of the great musicals in the canon deal with hate, social turmoil, madness, mental illness, family dysfunction, mob violence, pain, despair. (For some fine examples, see Sondheim, Kander and Ebb, Miranda.) But they do so with grace, irony, and respect — for the characters and the audience.

I have no doubt that Mitchell and his artistic team have noble intentions: Tell a gay love story that endures against all odds; describe a divided community that undergoes a moral transformation. But there are some fundamental problems here, matters of taste and sensitivity, that will have to be addressed if the show is to have a future beyond the Alliance. For now we can only wonder: What were they thinking?

THEATER REVIEW

“Becoming Nancy”

7:30 p.m. Wednesdays-Thursdays. 8 p.m. Fridays-Saturdays. 2:30 p.m. Saturdays-Sundays. 7:30 p.m. Sundays. Through Oct. 6. $25-$85. Alliance Theatre, 1280 Peachtree St. NE, Atlanta. 404-733-5000, alliancetheatre.org

Bottom line: Means well, runs amok.