Jane Jacobs versus Robert Moses. It's a David-and-Goliath story from 20th-century New York that defines contemporary urban debates and Matt Tyrnauer tells the tale well in this gorgeous, tightly written and entertaining film. Moses personified the alliance of big government, business and Modernist planning called "urban renewal." Jacobs, of course, was the writer-activist who opposed it all. Her book The Death and Life of Great American Cities in 1961 revealed the value of informal community and "the sidewalk ballet." As a history of this war of ideas and as an introduction to Jacobs, the film is essential. But it also pivots toward a great challenge: today's global urbanization. The towers-and-highways thinking that failed in North America is being re-enacted. "China today is Moses on steroids," says the academic Saskia Sassen. But Jacobs's bottom-up approach offers no clear answers about how to house and serve tens of millions of people in short order, and neither, really, does the film. It sets quite the challenge for dinnertime conversation.