14-year-old Elle Fanning is some sort of phenom, an actress both wise beyond her years and incapable of striking a false note on screen. She is just about the only reason to see "Ginger & Rosa," but if one wishes to watch Fanning's talents in action in far superior films, look no further than 2010's "Somewhere" and 2011's "Super 8." Writer-director Sally Potter, who introduced the world to Tilda Swinton with 1993's breathtaking "Orlando," is on much more wobbly ground this time, telling the story of two teenage girls growing up in 1962 London. Both were born at the same time, side by side, as the nuclear bomb fell on Hiroshima in 1945. Now older, Ginger (Elle Fanning) and Rosa (Alice Elglert) are largely inseparable, but going in different directions. With the Cuban Missile Crisis looming in people's minds, the more thoughtful, politically conscious Ginger has begun attending "Ban the Bomb" meetings, struggling to preoccupy herself as she faces a terrible truth: that Rosa has begun a not-so-secret affair with Ginger's father Roland (Alessandro Nivola).

When discussing "Ginger & Rosa," which had a one-week Oscar-qualifying run in Los Angeles prior to its planned 2013 opening, most viewers will focus on Elle Fanning's lovely performance because, frankly, there's little else worth recommending. The supporting cast, including Christina Hendricks (2011's "Drive") as Ginger's bitter mother, Oliver Platt (2010's "Love and Other Drugs") and Timothy Spall (2010's "The King's Speech") as her godfathers, and Annette Bening (2012's "Ruby Sparks") as their self-confessed militant friend, are oddly cast in nothing roles, their appearances calling attention to them for the wrong reasons. The plot, or what there is of one, feels scattered and vaguely aimless, heading toward the kind of uneventful finale that will leave more than a few audience members wondering if that's really all there is to it.

What is left, then, is one supremely fine performance at the service of material not nearly her match. Elle Fanning, an American taking on a seamless British accent and playing someone several years older than she actually is, brings a ruminative maturity to the poetry-writing Ginger. Preoccupied with existential thoughts about dying and what may or may not be waiting on the other side, her life appears to be heading in the direction of someone who truly wants to make a difference. When she finds out about the relationship between her best friend and father, she can't help but feel betrayed by both of them. Her bonds with both of them will never be the same—a tragedy in its own way, yes, but one that writer-director Sally Potter fails to find the enormity within. Instead, like the rest of the movie, it comes off as little more than an afterthought without a destination. Fanning sees the humanity in Ginger, though, refusing to fall victim to the picture's ho-hum wave. She gives it her all, but is deserving of a better showcase than "Ginger & Rosa" offers her.