U.S. missionaries introduced volleyball to China in the early 20th century, but by the time the sport returned to these shores it had mutated into a street-ball variation known as “nine-man,” Played mainly in Chinatown districts, nine-man even has an annual North American tournament, which first took place in 1957. This documentary by Ursula Liang hinges on the 2010 tournament, held in Boston over Labor Day weekend, and reaches back in time to explore the game’s powerful appeal to immigrant communities. For the old-timers interviewed, nine-man provided an antidote to the Caucasian stereotype of Chinese men as emasculated laundry and restaurant workers, and gave immigrants a chance to find out what life was like in other Chinatowns. Several generations later, the game has become a tradition rooted in racial purity: all six men on a team’s front line must be of full Chinese descent, and all three men on the back line must be of some Asian descent. (Women need not apply.) These rules strike some young players as archaic, though as one of them observes, “How can you tell people they have to share the only thing they have for themselves?”