Gael Garcia Bernal as René Saavedra in “No.” (Photo by Tomás Dittburn, Courtesy of Sony Pictures Classics)

Part political procedural, part seamlessly re-created time capsule, Pablo Larrain’s “No” re-visits Chile in 1988, when brutal dictator Augusto Pinochet — under pressure from the international community — held a plebiscite on his leadership, which he had seized in a coup in 1973.

“No” follows the quixotic advertising campaign mounted to remove Pinochet from power. Gael Garcia Bernal stars as Rene Saavedra, a brash young advertising executive who masterminds a media strategy that infused an inherently negative word (“no”) into a vote for progress, optimism and change. Using the anodyne motto “Happiness is Coming,” Saavedra co-opts Madison Avenue ad strategies to create a down-with-dictatorship/up-with-people campaign, replete with peppy musical numbers, idealized tableaux of pretty people in telegenic settings and, almost always, at least one winsome mime.

Saavedra’s boss happens to be working for Pinochet’s campaign, and his estranged wife, Veronica (Antonia Zegers), is a radical activist who insists that the plebiscite is just an empty exercise, rigged to legitimize a reign of terror that included murders, kidnappings, exiles and “disappearances.” Played by Bernal with somber reserve, Saavedra glides through the tensions of his life with cipher-like diffidence, hanging back meekly when Veronica is being beaten by police and quietly accepting her inconsistent presence with him and their young son.

Seen through one lens, Saavedra is a metaphor for Chile itself, the embodiment of the very passivity and fear that he’s trying to banish in a series of catchy 15-minute ad montages every night before the vote. But that might be reading too much into what is essentially a simple, uncomplicated retelling of events, albeit one made more aesthetically compelling by Larrain’s use of 1980s-era video technology and the appearance of real-life ad campaign actors. The result is one of the most naturalistic, spontaneous-looking period pieces in recent memory — one that isn’t afraid to look as bad as the era’s cheesiest visual culture (“No” is full of flares, glares and awkward cuts endemic to the proto-video age).

Some wags have called “No” a mash-up between “Mad Men,” “The War Room” and “Missing,” but it doesn’t quite achieve their brio or haunting power. Still, it’s an intriguing artifact, and Larrain is sophisticated enough to embrace and let stand Saavedra’s indeterminate position between social change agent and slickster. He’s so unforthcoming that it’s difficult to decide whether he’s hopelessly shallow or shrewdly un-threatening, but by the film’s tumultuous final scenes, his ambivalence is clear. “No” isn’t nearly as definitive or declarative as its title: It leaves viewers wondering whether they should cheer, shrug or shake their heads.

R. At Landmark’s E Street Cinema and Landmark’s Bethesda Row Cinema. Contains profanity. In Spanish with English subtitles. 110 minutes.