profession -- a booming sex industry that today experts say thrives on young girls threatened and coerced. for traffickers, it's never been safer to make millions. the men who sell women can hide themselves behind a girl they advertise on the internet. >> we take it very seriously. we've been working with the fbi for years. >> this is a craigslist operation. >> the oakland, california police department trafficking task force has conducted internet sting operations for years. to find exploited girls, they simply follow the internet trail. >> this girl i want to get to. she's 17. >> it's thursday night and oakland pd's human trafficking task force gears up for an undercover sting. >> the undercover officers will be out there in these vehicles in high prostitution areas cruising around. >> tonight oakland's task force will send six new undercovers out on the streets to pose as johns looking to pay cash for