World Finance of Greenville, S.C., rakes in half-a-billion dollars a year providing small loans to subprime borrowers. Thanks to an ever-deepening cycle of debt, business is good.

A federal law is supposed to protect service members from predatory lending. But lenders exploit loopholes, trapping military personnel in high-interest debt.

World Finance, a billion-dollar company, peddles installment loans, a product that often drives borrowers into a similar quagmire of debt.