JUST FOR FUN, I took an online quiz after watching Citizen Koch. "How well do you know Charles and David Koch?" it asked, and it turned out I didn't know much at all about the oft-maligned Koch brothers, freshly watched documentary or no.

The quiz included a lot of personal trivia: cancer diagnoses, the plane crash David Koch eerily survived ("the only passenger in first class" to do so). But there was meaty stuff, too, like a past vice-presidential run, formative educations, and family history.

It's not remotely fair, but my failing to score well on that meaningless Politico clickbait is also Citizen Koch's failing.

The film's titular villains—the oil-piping, timber-harvesting masterminds behind Koch Industries and the Tea Party-fueling Americans for Prosperity—seem to have their sticky billionaire hands in any nefarious conservative scheme you'd care to point to. The bulk of America, meanwhile, has no idea who the two are, according to polling done in April. More sunlight can only be a good thing.

But the film casts a narrow beam, busying itself with the more obvious narratives that have emerged around the Kochs in recent years and failing to offer much new illumination. It begins with Citizens United v. Federal Elections Commission, the devastating US Supreme Court decision that's spread the American political system wide open for corporate money. Then the filmmakers, Carl Deal and Tia Lessin, hang out in Wisconsin, exploring Governor Scott Walker's anti-labor scheming and teasing out connections between Walker's political power and his Koch money.

Along the way, we meet pro-life farmers and confederate flag-flying bikers and juiced-up prison guards—Republicans, most of them—who are sick over Walker's antics. And we tag along, briefly, with former Louisiana Governor Buddy Roemer who, absent the blessing of corporate cash, couldn't get a second look from Republicans during 2012's heated primary season.

Citizen Koch has fine, compelling snapshots. But the film—unlike the excellent recent documentary Inequality for All, now on Netflix—misses a bigger chance to expound on why they matter. And it leaves the intrigues of the brothers Koch as mired in shadow as a theatergoer. It's a safe bet that's how the Kochs prefer things.