Shot in a quasi-documentary style (and an old aspect ratio) that go oddly well with an uplifting story about a country’s peaceful liberation from dictatorship, Pablo Larrain’s “No” is a fact-based account of a 1988 referendum that unexpectedly led to the end of General Augustin Pinochet’s rule in Chile. But while the impact of the vote, which the General agreed to only under international pressure, is the film’s overarching theme, Larrain—working from a script by Pedro Peirano after a play by Antonio Skarmeta, concentrates on the advertising campaign that turned the electoral tide against the ruling junta. Smoothly juxtaposing starkly serious sequences against moments of dark and not-so-dark humor, Larrain fashions an unlikely crowd-pleaser from a historical episode that has its share of tragedy as well as triumph.

Gael Garcia Bernal stars as Rene Saavedra, a hotshot young adman at a cutting-edge firm specializing in glitzy, unconventional TV spots for products like a soft drink called Free. Estranged from his far more activist wife( Antonia Zegers) but still closely involved in the life of their young son (Pascal Montero), he’s initially reserved when approached by a leftist politician (Luis Gnecco) to join the group planning the campaign to urge citizens to vote against Pinochet’s continuance as president. But eventually he joins up, despite the danger that poses to himself and his family and the fact that his boss Lucho (Alfredo Castro) has been hired by the government for their “Yes” campaign. So there’s an amusing personal competition added to the far more serious mix.

The linchpin of the plot is the direction the “No” advertising took under Saavedra’s influence. Instead of going a heavy, ponderous route, reciting woeful facts and figures about an admittedly dark time, the TV spots opted for a bright, optimistic tone that emphasized the feeling of liberation and freedom the dismantling of the oppressive Pinochet regime would bring. And though the commercials—made surreptitiously with the participation of show biz folk who yearned for change—were relegated by the government to late-night hours when it was presumed they’d go unnoticed, their neon-colored visuals and witty commentary on the years of oppression became a sensation, forcing Lucho to try to respond in kind. And when the vote is finally taken, the regime’s initial inclination to manipulate the result in Pinochet’s favor has to be scuttled when his fellow junta members refuse to go along; and though the General retained his position in the military, his forced laying down of the presidential office became for Chileans a sort of second independence day.

Larrain tells this story in a fashion that combines the seriousness of a Costa-Gavras with the feel-good mentality of a Frank Capra. One wouldn’t expect the mixture to be a plausible one, but he pulls it off, not least because Bernal cuts, as always, a charismatic yet approachable figure as Rene, and the more reserved Castro makes such a perfect foil for him. And the film is cleverly constructed from a technical standpoint as well, perfectly blending archival footage from the eighties with the newly-shot material by employing actual 1983 U-matic video cameras and film stock from that time, as well as the boxy aspect ratio that’s now considered antiquated. The result, which must have given cinematographer Sergio Armstrong plenty of headaches, proves to have been worth the effort, giving everything a decidedly documentary look. But the effect wouldn’t have been possible without the extraordinary attention to period detail that’s obvious in the work of the behind-the-scenes crew—especially production designer Estefania Larrain and costumer Francisca Roman. And though this won’t mean as much to non-Chileans, the presence of many participants in the actual events—including Saavedra—in small roles adds to the sense of authenticity.

The subject of “No” might initially seem parochial, and to a non-Chilean audience relatively inaccessible. But in reality the struggle against tyranny, wherever it exists, has universal resonance. (After all, Pinochet eventually became a target of international efforts to prosecute him, though they never succeeded.) Most treatments of such matters, however, are understandably sober, even grim. By contrast Larrain has been able to deal with this episode in what might be called a lighthearted fashion without sacrificing the genuinely tragic undertones of a dark period in his country’s history. You leave his film instructed, but also entertained—an excellent combination.