(CNN) By providing a ground-floor seat to the start of the Alexandria Ocasio-Cortez phenomenon, "Knock Down the House" feels like an extended window into a moment in history. That fortuitous twist, however, risks overshadowing the documentary's larger message, which essentially serves as a rallying cry to brave elected politics, emphasizing that AOC is the notable exception, not the rule.

Directed and co-written by Rachel Lears, the movie -- which sold to Netflix for a reported $10 million at the Sundance Film Festival -- meticulously chronicles several Democratic activists mounting challenges to well-established incumbents.

While Ocasio-Cortez understandably garners the lion's share of screen time, her experience is cast in the context of a movement, with the filmmakers spending time with other contenders -- Cori Bush, Amy Vilela and Paula Jean Swearengin, each with their own stories -- in Missouri, Nevada and West Virginia, respectively.

The Darwinian lesson, as a consequence, takes time to come into focus, and is specifically articulated by Ocasio-Cortez near the end, when she observes as a note of consolation, "It's just the reality that in order for one of us to make it through, a hundred of us have to try."

Perhaps what "Knock Down the House" does best, in that context, is highlight the enormous odds that Ocasio-Cortez had to overcome, as well as the dismissive nature of her opponent, the congressional veteran Joe Crowley.

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