Title characters Ginger and Rosa are best friends.
Vanguard baby boomers born in adjacent London hospital beds in 1945, they are teenagers in 1962, when most of Sally Potter's ardent and intelligent film about the girls takes place.
The air around them is charged with anxiety about the threat of nuclear war, mostly intellectual restlessness and sexual curiosity.
Perhaps it always is that way for 17-year-olds, but every generation acts out its own particular pageant of rage, revolt and disillusionment.
The dark-haired Rosa (Alice Englert), whose father abandoned his family when she was small, is wilder and sadder than Ginger (Elle Fanning), whose red hair stands out amid the ambient browns and grays that signify the pre-swinging, as-yet-un-Beatled England.
On some of their adventures smoking cigarettes, making out with boys, hitchhiking to the seashore Ginger seems to be following her friend, hungry for Rosa's company as much as for the thrill of illicit experience.
Rosa, for reasons perhaps too neatly accounted for, is a risk-taker who does poorly in school and regards her mother (Jodhi May) with undisguised contempt.
Ginger, in contrast, is rebellious in ways that show her to be responsible and disciplined rather than impetuous. She writes poetry and goes to Ban the Bomb meetings and rallies, and seeks the approval and company of at least some adults.
She is delighted when her cleverness and commitment are noticed by her gay godfathers, both named Mark (Timothy Spall and Oliver Platt) and by their friend Bella (Annette Bening), an American writer of uncompromising seriousness.
Above all, though, Ginger worships her father, Roland (Alessandro Nivola), who seems, after his own scruffy intellectual fashion, as dashing and romantic a figure as his literary namesake.
"You're a born radical," he tells his daughter, which pleases her even though he means it primarily as self-praise.
In his own account at least, Roland, a writer and teacher who was imprisoned as a conscientious objector during World War II, has devoted his life to fighting tyranny and flouting convention.
Eventually he invokes these principles to justify an almost unimaginably appalling but also, in its way, perfectly ordinary betrayal.
"Ginger & Rosa" a coming-of-age story planted in the overplowed field of the mythical 1960s is more conventional than some of Potter's other films, like "Yes," with its rhymed dialogue and geopolitical gestures, or the gender- and history-defying "Orlando."
Her impeccable sense of color and composition, and her use of montage and careful sound design as a kind of emotional shorthand, are used here in the service of novelistic psychological realism.
The period details all seem just right not only Ginger's copy of T.S. Eliot's poems and her jazz records, but also the general atmosphere of British left-wing bohemianism.
Some of it may be a bit too perfect and programmatic, and the film's adult characters sometimes seem more like types than people. (This is especially true of Natalie, Ginger's unfulfilled, disapproving mother, played by Christina Hendricks, who struggles nobly to find nuances in the role and to get a handle on her accent.)
Such flatness may be intentional, since part of the narcissism of adolescence is a tendency to view grown-ups as caricatures and supporting players in one's own drama. Ginger, smart as she is, is blind to both Roland's flaws and Natalie's virtues, and the film is in part the story of her eyes being brutally opened to the truth about her parents.
But it is also true to its title, the chronicle of her relationship with Rosa.
Their bond is ultimately undone by an act of treachery that pitches the film toward melodrama, forcing unspoken emotions to erupt in furious scenes that should be more devastatingly believable than they are. But nearly everything else here has the ring of truth, in no small part because of the two remarkable young actresses in its title roles.
Fanning, who is younger than her character, shows a nearly Streepian mixture of poise, intensity and technical precision. It is frightening how good she is and hard to imagine anything she could not do. What she does here is convey the inner life of a girl witnessing and undergoing tumultuous changes.
Rosa is mostly seen through Ginger's eyes and is not as articulate or as analytical as her friend. Her motives are not always clear to her, and she can be thoughtless and cruel in ways that would never occur to Ginger. Englert is as adept at blurring Rosa's feelings as Fanning is at clarifying Ginger's. Between them they illuminate an intimate, volatile cosmos.
GINGER & ROSA
Cast: Elle Fanning, Alice Englert, Alessandro Nivola, Christina Hendricks, Timothy Spall, Oliver Platt, Jodhi May and Annette Bening
Director: Sally Potter
Rated PG-13 (Sex, smoking, nuclear anxiety)