FRONTLINE offers two starkly contrasting images: one of empty storefronts in Circleville, Ohio; the other, a sea of high rises in the South China boomtown of Shenzhen. The connection between American job losses and soaring Chinese exports? Wal-Mart. For Wal-Mart, China has become the cheapest, most reliable production platform in the world, the source of up to $25 billion in annual imports that help the company deliver everyday low prices.