Brooklyn Castle is a documentary about I.S. 318 — an inner-city school where more than 65 percent of students are from homes with incomes below the federal poverty level — that also happens to have the best, most winning junior high school chess team in the country. Chess has transformed the school from one cited in 2003 as a "school in need of improvement" to one of New York City's best. But a series of recession-driven pubic school budget cuts now threaten to undermine those hard-won successes.