“I’m your Ch-ch-ch-ch-ch-Cherry Bomb!” belts Cherie Currie (Dakota Fanning), the chaotic lead singer of The Runaways. Sorry Britney, but in 1975, the 15-year-old rock starlet patented the jailbait double entendre. Still, writer-director Floria Sigismondi’s biopic makes it clear that Cherie didn’t invent the teen temptress. The role was thrust upon her by producer/Svengali Kim Foster (Michael Shannon) who wrote her come-ons and dared her to take the act further. He knew a girl group led by a half-naked blonde would sell—he just needed a girl who looked the part, and when he spotted the fashion-obsessed Encino hipster, he molded her into a tabloid Lolita. (Yes, even in the early days of punk, looks mattered.) Like Foster, The Runaways puts music second. It rocks attitude and sex, drugs, abandonment and kisses between Fanning and Kristen Stewart’s Joan Jett. Jett anchors the movie’s first half—she was ready to rock before she could play her guitar, and when she straps on that weapon, we see a girl determined to blast through any barrier. There’s a tough pulse to this boozy drama which takes a genuine interest—at least, for a while—in the friendships and femmepowerment that powered the band (though it makes Scout Taylor-Compton’s Lita Ford a whiny crank). It’s a feminist piece only in that it says chicks can drink, scream and screw as wild as any Rolling Stone. Thirty-five years later, their antics are bracing—we’ve been pacified by Vanessa Hudgens. Sigismondi’s film is flush with the invulnerability of youth. Moments of it feel fully alive like those last drunken whoops before a post-prom car crash. As Jett, Stewart is steely and aloof. She graces us with her cool. But this is Fanning’s movie and she cranks it up to 11. Fanning’s not just a brave young actress; she’s a brave actress. In every scene of the movie, she fights—and wins—her battle for an adult career. Cherie’s drug addiction swallows up the last half of the movie (as it also did the band’s fortunes), and though Sigismondi shunts aside her more interesting themes for a rote plot she can’t shape into a credible climax, Fanning is a scary, sexy force—awesome in every sense of the word.