When you’re a teenager, a rift with your BFFmay feel like the end of the world. In Sally Potter’s Ginger & Rosa, set during 1960s London as nuclear warfare becomes an increasing possibility because of the Cuban Missile Crisis, both scenarios are equally real to one politically savvy teen, whose anxiety over the bomb deepens as a lifelong friendship crumbles.

The film starts with ominous music and a mushroom cloud before transitioning to a maternity ward in 1945, when Ginger (Elle Fanning) and Rosa (Alice Englert) were born on the same day. Since then they’ve been inseparable, smoking cigarettes, hitchhiking, and even nearly kissing before they burst into a fit of giggles. But they also talk about their semi-broken homes—Rosa grew up without a dad, while Ginger’s, Roland (Alessandro Nivola), is a promiscuous activist who makes her mother (Christina Hendricks) unhappy—as well as the threat of nuclear disaster, which they protest, though Ginger is more earnest. “How can anyone be happy?” she asks Roland (she doesn’t call him dad). “We know about the bomb.”

As Ginger is wringing her hands and writing poetry about what she feels is an inevitable armageddon, Rosa becomes busy flirting and exchanging letters with someone she’s developed a “connection” with. Suddenly she’s too busy putting on makeup and having sex to care about nuclear warfare, and Ginger becomes more glum, then angry.

Ginger & Rosa is writer-director Potter’s least pretentious film to date—let’s all forget The Tango Lesson, in which Potter starred as herself—shot in a non-attention-calling style and not jammed with lofty ideas beyond political dissent and atypical attitudes about family life. The dialogue is occasionally a little stiff; more distracting is Hendricks’ British accent, which the Mad (wo)Man appears to be trying a little too hard to pull off.

As seems to be the norm these days, the highlight of the film is Fanning, whose accent is natural, and her merry-go-round of nuanced emotions. Her Ginger, aside from the story’s cheery beginning, is perpetually depressed, tortured, and preoccupied, certain that as her friendship dies, so will die the world. Englert’s Rosa successfully evolves too, from a carefree girl to an anxious-to-mature woman; the deepening chasm between the two friends feels quite real. They make you believe that war at home is usually more soul-crushing than war in the world.