Inside the world of Cambodia's child sex trade, as told through the eyes of a survivor

— -- At first glance, 22-year-old Sokha Chan might seem like your average young California girl. She has a lap dog named Chica, and her own car that she bought herself.

But behind her seemingly charmed life, Sokha hides a dark past from her childhood that still haunts her to this day. And for the first time, she’s decided to travel 8,000 miles to confront that past, going back to where her life started in Cambodia.

Cambodia is often called “The Kingdom of Wonder,” but turn down certain side streets and there is a sordid world where sex is the hot commodity and children are still used as currency. It’s a country that was almost destroyed by civil war and genocide, and experts say it was out of that brutal and lawless period, following the fall of the Khmer Rouge, that prostitution and child sex trafficking began to flourish.

Sokha grew up in a poor village near Phnom Penh, the capital city. She said she was just 7 years old when she was sold for sex to an American man named Michael Joseph Pepe, a former U.S. Marine, who was then living as an ex-pat in Phnom Penh.

“He won my virginity,” Sokha said. She did not know why he had come to Cambodia to buy a child like her for sex.

“Nightline” obtained hidden camera footage of several Western men who appear to be soliciting sex with underage girls in Cambodia. At one point, a man could be heard asking for a 10-year-old girl. Another asks for a 14-year-old, while another said he would take an 8-year-old.

The video was shot over the last two years by Agape International Missions, or AIM, an organization dedicated to fighting child sex trafficking in Cambodia. Despite progress made by the government to crack down on the issue, it is still a major problem in the country.

Former pastor Don Brewster and his wife Bridget founded AIM to protect Cambodian children, like Sokha, from men like the ones captured on video. Don Brewster says pedophiles will come to Cambodia for sex because “they can get away with it.”

“The [pedophiles] are ending a childhood,” he continued. “They may not [end] a life, but they're killing a child in the sense that a childhood is gone that'll never be regained. Sokha will never have a childhood.”

Officials say the problem is getting better. Prostitution is now illegal, but Don Brewster says it is still rampant in Cambodia, operating out of massage parlors, bars and karaoke lounges. And in some back rooms, underage girls like Sokha are still being abused and sold for sex.

The Brewsters say what happened to Sokha was a “virgin sale,” and it was just the beginning of her horrors in the sex trade. Sokha says she spent years shuttled to different illegal brothels, always locked in a dark room.

“If you see that room, you would know that I'm going to die in there,” she told "Nightline." “That room is so dark and doesn't have everything. Doesn't have the light, doesn't have the restroom, doesn't have nothing.”

“And I cry every day,” Sokha continued. “I [was] scared every moment, and now I [am] still scared of the dark. When I sleep at night, I don't close my eyes … because I feel like they [will] call me out of the room, and do something on me.”

When she was 12 years old, a miracle happened: she was rescued.

“The gate opens and all the police came in and that's how they arrest them,” she said.

Sokha was freed by an NGO working with the Brewsters. When he first met Sokha, Don Brewster said she was really shy and quiet, and suffered from a “pretty significant” tic.

They brought Sokha to their long running aftercare center, where victims of child sex trafficking come to heal. The center is one of the multiple facilities AIM operates in Cambodia. The horrific undercover videos obtained by "Nightline" were filmed on the same streets where the Brewsters now live.

“There’s no shame … coming into a little community like this, stopping in front of the school back there and asking the first person you see, ‘I want to have sex with a young girl,’” Don Brewster said.

The Brewsters said every building of their facility in Svay Pak, once known internationally as a hotbed for child prostitution, used to be a brothel that sold children -- some as young as 8 years old.

“This was the worst brothel in a village that was brothel after brothel after brothel,” he said. “I say the worst because this is where the kids were hurt, this is where the young kids were the 8, 9, 10, 11-year-old kids were housed in this building.”

As Don walked "Nightline" through one particular building, he pointed out a room where he said kids were trapped and forced to have sex with strangers.

“There was no lights down here,” he said. “The back door was cemented close so they couldn’t escape out the back way.”

The Brewsters say they know many more girls like Sokha are still out there, unable to escape. Two years ago, with the help of some donors, they created their own brothel-raiding SWAT team, working alongside the Cambodian National Police, to capture traffickers and rescue girls.

Eric Meldrum, a Scottish-born former U.K. police officer, leads the AIM SWAT effort. AIM took “Nightline” inside a raid to take down another alleged sex trafficker known as “the mama-san.” Meldrum called her “the main trafficker” running the brothel they wanted to raid and said she was using a massage parlor as a front.

After several tense hours, the investigators raided the brothel, isolated and arrested “the mama-san” and rescued several young girls, including two minors. They were taken to a police station with AIM social workers.

Just three days after being taken out of the brothel, Don Brewster and the AIM team welcomed the girls to their facility where they all were given new clothes and crowned with a tiara. It’s an AIM ritual that every rescued girl is presented with a princess crown.

Ten years ago, Sokha was one of those girls to receive a tiara. She said her freedom has meant everything to her.

“I want ending of the trafficking,” she said. “I want to help another girl.”

Many girls arrive at the AIM facility often feeling like they have no value, no longer able to earn money for their families, even if those families are the ones who sold them in the first place.

AIM told us that Sokha’s mother was the one who sold her daughter to Michael Pepe, an American who was extradited to the U.S. and convicted of seven counts of illegal sex acts with a child in 2008. The crimes were all committed in Cambodia and all seven of the girls are Cambodian, one of which Sokha. . He was sentenced to 210 years in prison in 2014.

“I [was] angry at her and I did cry about it,” Sokha said. “I told her, ‘I can do everything for you, like go sell fruit at the market, I can do that, but please don’t sell me.’”

Sokha obtained a visa to move to the U.S. after testifying in Pepe's trial. She works as a nail technician and a baker, attends church, and lives with an American family.

Sokha took "Nightline" back to her village, to confront her mother about what happened to her 15 years ago. Her mother told us she was extremely poor, and when a woman said a café needed a waitress and offered her $100 a month for her daughter, she jumped at the chance. She denied knowing the café was a front for a brothel. But Sokha says the more unforgivable thing her mother did was selling her virginity to a pedophile.

When Sokha asked her mother why she put her in Micheal Pepe’s house, her mother said she gave her over to work as a maid for him, but she denied selling her to him.

Then, for the first time, Sokha revealed to her mother, in great detail, some of the awful moments she faced as a little girl -- being beaten, forced to take drugs and have sex with strangers. Sokha’s mother asked Sokha if she could forgive her for the wrong she did to her in the past, to which Sokha told her mother she forgave her. At the end of their conversation, both women were in tears.

Sokha has a new life, which she says is a better life, and has tried to move past these years of fear and darkness.

When she was a little girl, Sokha said she felt like “the ugly one in the world,” who no one loved. But now, she said, “I am a princess.”

ABC News' Ashan Singh, Gamay Palacios and Lauren Effron contributed to this report