The story of the eponymous all-girl rock band assembles some backstage clichés to facilitate the continued growth, right before our eyes, of Kristen Stewart and Dakota Fanning, as guitarist Joan Jett and vocalist Cherie Currie respectively. “This isn’t about women’s lib,” announces their mid-Seventies Svengali. “This is about women’s libido.” (Tiredest cliché, twice used, is the dreaming of dreams beneath the Hollywood sign.) You might expect a degree of candor in a movie that starts out with a splash of menstrual blood (Fanning) on the pavement outside the Pup ’n’ Fries, or that permits revenge to be taken on a chauvinist-piggy rock star by peeing (Stewart) on his guitar. And yet, in first-time filmmaker Floria Sigismondi’s screenplay, we hardly get to know these people beyond Currie’s curious tolerance for the sappy “Starry Starry Night” of Don McLean. Was that Sapphic kiss just a kiss? Was there ever a sequel to it? Or is it simply another growth spurt for Stewart and Fanning? In the void, the movie emerges as scarcely more than costume-party dress-up. (Theme: the Me Decade.) The two leads unquestionably look their parts — the jet-black Jett with her Kabuki hair and the jail-bait Currie, “a little Bowie, a little Bardot,” and, we might add, a little Lolita — but their natural modes, Stewart’s tortured introversion and Fanning’s fawnlike timidity, are a lot to overcome in the roles of barrier-smashing rockers, and they neither of them overcome it. (2010) — Duncan Shepherd