THE SHAGGS: PHILOSOPHY OF THE WORLD, Lookingglass Theatre Company. Pure nonfiction is a mythical beast: the carefullest journalist still colors the tale, and in entertainment “based on” real events, what’s compelling routinely trumps what’s true. But given the premium on authenticity in outsider art, embellishing the biographies of its luminaries is singularly problematic. And in this musical-theater version of the story of the Shaggs, the original aboriginal girl band, playwright Joy Gregory has rewritten more than enough of their history to obscure its real shape.

You can see why some accessorizing was necessary. There’s little information on the Wiggin sisters beyond the broad outlines: in the late 60s, three talentless hayseeds from Fremont, New Hampshire, were coerced into the service of rock ‘n’ roll by their crackpot/visionary father, who was forcing the fulfillment of his ma’s prophecy. Ignored in their day, the Shaggs were later rediscovered by various hipsters, eventually becoming a Rorschach test for music and art theorists alike. But Gregory’s bending or omitting what’s known while amplifying the details tailor-made to Hollywood formula backfires mightily. For example, turning producer Charlie Dreyer into a loudly dressed schmoozer sets up a wonderfully Robert Preston-esque sales song–but the real Dreyer was a black-clad enigma known for his engineering skills and abysmal salesmanship. The show is thoroughly entertaining on a superficial level: the production values are splendid, the songs are winning, and the cast is stellar. But the actual Shaggs–as well as the critical conundrums they raise–end up overdubbed.