Shrimp is big business in Thailand, thanks to an appetite in the United States that continues to grow. Today, a third of country's exported shrimp goes to the U.S., its top customer, where retail giants like Walmart and Costco do high-volume sales and suburban Red Lobsters offer bargain blue plate specials. Breakthroughs in aquaculture have helped Thai producers keep up with the rising demand, but there's a catch to their success: an invisible underclass of Burmese migrant workers, thousands of whom labor in sub-human conditions to keep costs down. Of the estimated 200,000 Burmese migrants working in Samut Sakhon province, the heartland of the Thai shrimp industry, about a third are unregistered and subject to rights abuses. Independent monitors say that thousands desperate to escape the poverty and dictatorship of their homeland cross the border only to find themselves trapped in bonded labor that's tantamount to slavery. Sold by brokers to crooked factory owners, they are forced to endure long hours for pitiful wages, physical abuse and intimidation. Many are children who do not meet Thai working age requirements. Their plight is made worse, critics say, by the profit-induced apathy of Thai authorities who turn a blind eye or are complicit in abuses. Reporters Steve Sapienza and Jason Motlagh investigate exploitative labor practices at the lower levels of the supply chain.