Editor's note: This article is part of The Fighters, a series of reports from a full-length film that premieres on CNN International TV on May 17 and 18 at 1900 HKT; 2200 CET; 2200 ET. The documentary is a result of two years of undercover work and filming in the Philippines.
Manila, Philippines (CNN) -- Birds chirp outside. A motorcycle groans up a nearby hill. And in a small, warm room filled with books and framed drawings, a young woman we're calling Maria tears at a tissue as she prepares to tell how sex traffickers corrupted her life.
"I was 15 when I was recruited," she said. "I had to find a job because my father had a lung problem and I needed to find money so we could send him to the hospital."
Maria met a person in her province who said he could find her a job in Manila.
"I thought I was going to work as a dishwasher in a restaurant," she said. "But when I arrived I realized it was a 'casa.'" 'Casa' is a code word for brothel in the Philippines.
Many young girls fall prey to human traffickers. They often leave their homes and villages in the provinces, seeking opportunities to support their families.
The traffickers are adept at convincing them to travel with them.
"I traveled through the islands. It took me 24 hours to reach Manila. When I got there, I found 16 girls staying in the same small place. Some were as young as 13-years-old," she said.
Maria was trapped and forced to have sex with a number of foreign and Filipino men.
Although she was there for only a few weeks before the Filipino police raided the apartment and freed her and the others, the damage had been done.
Maria routinely saw up to 13 customers a day. Her captors forced her to go to extreme lengths to deceive them into thinking she was a virgin in order to command higher prices.
"We were forced to take a cotton ball and dip it in pigeon's blood, then put that in our sex organ," she says. As outrageous as that is, it is not unusual.
In some parts of Asia, anti-trafficking groups have found that men believe sex with a virgin can cure their HIV/AIDS.
Social workers say that's led to a disturbing trend with tragic consequences for the victims of human trafficking. UNICEF estimates as many as 100,000 children work in the illegal sex trade in the Philippines.
Many women are also forced to prostitute themselves, not because of financial circumstances, but because they fear violence against themselves or their families, if they try to escape.
While filming the CNN Freedom Project documentary, we interviewed three girls, whose story was so profound and distressing, it left me in tears, the only time in my 15-year career that's happened.
The interview started out normally, with the girls singing into the microphone and telling us about Tom & Jerry cartoons and the crushes they had on the musician Bruno Mars.
They seemed like typical 12-year-olds, but what they would tell us about what they'd been through, stopped me cold.
"The trauma is really so deep," says Cecilia Flores-Oebanda, the director of the Visayan Forum Foundation, an organization that cares for recued girls. "They wake up in the middle of the night screaming and crying because they are so afraid the trafficker will come again. Sometimes one of the kids suddenly gets sick and vomits. Our psychologist said it's because she remembers what these guys on the Internet asked her to do."
One of the girls said: "At the internet café they tell me to take my clothes off and then they make me dance [in front of the camera]. I was kind of embarrassed because I'm not used to being naked like that."
Often that wasn't enough for paying customers on the other side of the sex chat room. For $27 an hour, anyone could tell the girls what to do, and a man behind the camera would make sure they did it.
The girls told of men coming in off the street and the girls having to perform sexual acts. Animals were sometimes involved. And perverts took deranged pleasure in watching the girls suffer these terrible abuses.
"Sometimes we had to urinate," says the girl in the middle. Her friend to the right adds: "The urine is mixed with juice as a drink."
"That's what the American client wants. He demands anyone who feels like urinating should do so, but that he wants us to do it in front of the camera."
I asked the children what they think about Americans.
"You're maniacs," one of the girls says, sharply. "You need to stop victimizing girls like us."
The Visayan Forum Foundation, which has operated in the Philippines since 1991, says it has reached out to more than 70,000 victims or potential victims of human trafficking, and provided services to, or helped rescue, more than 15,000 victims.
"The cases we handle in the Visayan Forum is always on trafficking for prostitution and domestic servitude," says Oebanda. "Now there's a new phenomenon of trafficking for cybersex. We observe that [the victims] are becoming younger and younger."
During filming, we witnessed several raids conducted by the Philippines Inter-Agency Council Against Trafficking, referred to commonly as IACAT.
One of those raids involved two suspected traffickers and four teenage girls coming in to Manila aboard a passenger ferry. Officers with the Coast Guard and Port of Manila police intercepted the group before they could disembark.
"One of the [girls] is around 15 years old and another one is around 16 or 17 years old, so that's a qualified case of human trafficking," says Oebanda.
They told social workers they were heading to a city north of Manila where the trafficker planned a live show in a cybersex den and where they would be prostituted.
Oebanda and lawyers with the Philippines' Department of Justice filed charges against the two suspects, realizing it could be years before the trial is finished.
New cases like these were always heartbreaking for Maria, whose own attempts to embrace a new life were cruelly snatched away. In March this year, she died from complications as she gave birth to her second child, social workers told CNN.
One of the last things Maria said to CNN was a message to warn others.
"Please, do not to believe all the promises, especially from people you don't know, because a lot of things can happen if you leave with them."