In their new book, Half the Sky, Nicholas and his wife, Sheryl WuDunn, investigate the causes and the very achievable solutions to putting an end to this form of modern-day slavery. "If you begin to think of your own child not in middle school, but being locked up in a brothel, then it suddenly becomes pretty real," he says.
Children like Long Pross, kidnapped from her Cambodian village at age 13, are forced into a terrifying world of prostitution. She had not yet had sex or her first period. "The fear was overwhelming," she says. "In a room they tied your hands, and outside there was a guard. If you resisted, they electrocuted you. Sometimes they electrocuted me twice a day if I argued too much."