Ever heard of I.S. 318? It's a public junior high school in Brooklyn that just happens to boast the best chess team in the country, and it's the focus of the new documentary Brooklyn Castle (out October 19), which won the Audience Award at South by Southwest. Still, despite the emphasis on winning, this is a film about underdogs, since I.S. 318 is made up principally of children who are below the poverty line and the school's budget slashes could spell doom for the kids' trips to chess tournaments. What would it mean for them to lose something that gives them such fire and ambition? Watch this exclusive trailer and find out.