The good news: Dakota Fanning has never acted so young in her life. The bad news: She’s just as creepy as ever.

Based on the story of the first commercially successful all-girl rock band in America, “The Runaways” tells the story of five schoolgirls who come of age on the road and quickly learn how the music industry can be your friend one day and screw you over the next.

The narrative focuses on good-girl-gone-bad Cherie Currie (Fanning) and rebelious guitarist Joan Jett (Kristen Stewart) as they grapple with the trials and tribulations of instant success on a global level. The band’s rise to glory is not an easy one; as Currie’s ego takes hold and their Bowie-esque manager Kim Fowley’s (Michael Shannon) ego inflates, the group sets off down the well-trodden rock-star path to self-destruction.

Not only has the story been seen and heard before — albeit maybe not with teenage girls, unless you count Josie and the Pussycat Dolls — director and screenwriter Floria Sigismondi makes no attempt to scramble the formula. Even a brief sexual relationship between Currie and Jett, which develops on the road, is so obviously foreshadowed from the moment the two meet in a grrrl-rock club that we’re impatiently waiting for the two to hook up for the rest of the film instead of watching the drama unfold.

But never fear, horny freshmen — that time does eventually come, and Sigismondi makes sure to slow the erotic lesbianism so we really get the full effect.

At first, Fanning plays her naive role with prowess, but her transformation into the band’s bad-ass vocalist is utterly unbelievable and more disturbing than most scenes from “Uptown Girls.” While tides of filmic fans lap up her rock-star attitude, Fanning’s sexy, glamorous Currie is just plain uncomfortable for those of us who still remember her as the fairy child from “I Am Sam.” Things get especially awkward when she shows up on stage in lingerie. The 16-year-old Fanning — who’s made a living up to now as a child actor in roles that require a 60-year-old soul — simply hasn’t matured enough to play a diva addled by drugs and life on the road.

Because the three other members of the group are pushed so far into the background, the fight that eventually erupts between Currie and her bandmates — bringing an end to the Runaways — has little buildup or explanation. With a disturbing lack of twisty characters or unexpected turns, “The Runaways” leaves little reason for us to become invested in the girls’ story. The only demographic that might be stoked enough to sit through the stock plot is the teenage girl grasping for a reason to rebel against her cush suburban society. Sound familiar, Fanning?