Poonam thus became one of 20.9 million people worldwide — a quarter of them children — subjected to forced labor, according to the U.N.’s International Labor Organization. In the United States, tens of thousands of children are trafficked into the sex trade each year.

Men visiting Poonam’s brothel paid $2.50 for sex and were sometimes oblivious to the brutality, flattering themselves that the girls liked their work. They see girls who often smile; no one is holding a gun to their heads.

Poonam responded with what so many others have said: The smiles are on the outside, even as girls are crying inside.

“We were told to smile, because a smile is money and will pull in customers,” Poonam said. The girls were also ordered to say that they were over 18 and working voluntarily.

Then one day police raided the brothel. Warned by the brothel owner that the police would torture her if they found she was a child or trafficked, Poonam claimed that she was 23 and working voluntarily, but the police could see that she was a child and took her to a shelter.

Indian authorities returned Poonam to the care of Maiti Nepal, a leading anti-trafficking organization. Now Poonam is studying to be a social worker in hopes of helping other trafficked girls. A new study suggests that post-traumatic stress disorder is frequent among those who have been trafficked.

Anuradha Koirala, founder of Maiti Nepal, notes that there has been a bit of progress against sex trafficking of Nepali girls. A crucial step, whether in Nepal or the United States, is ending the impunity for pimps and traffickers, and Koirala says that Maiti Nepal has helped prosecute 800 people for involvement in trafficking. In America as well, we need to prosecute traffickers rather than their victims.