"48 Hours" Live to Tell: A 15-year-old is held captive by a sex trafficker and Ashton Kutcher’s mission to stop children from being exploited

According to the FBI, sex trafficking of children in this country has become a nationwide problem. And traffickers target troubled girls with low self-esteem -- girls like Alyssa Beck.

Beck was just a naïve 15 year old living in Jacksonville, Florida, when she found herself trapped in a sex trafficker's web.  She would be in and out of their trap for almost five years.

CBS News correspondent Michelle Miller has been following Beck's story and the horrific world of sex trafficking of kids. It could happen to anyone – that's why actor and activist Ashton Kutcher has taken on this cause to save other young victims.