Synopsis: According to the National Center for Missing and Exploited Children, there are at least 100,000 underage females being sex trafficked in America today. That’s a conservative estimate based on what little hard data currently exists; NCMEC believes the real number could be as high as 300,000. According to studies, pimps can make up to half a million dollars a year, and they frequently prey on the young and the vulnerable over the internet — the new marketplace for underage sex trafficking. In 2011, victims’ advocates referred to the internet classified site Craigslist’s Adult Service Section the “Walmart of child sex trafficking.” In a yearlong investigation, CNN’s Amber Lyon reveals the devastating realities of the U.S. commercial trade in underage sex.