Transcript for Fighting Cambodia's child sex trade: Part 1
Tonight an extraordinary encounter. We're with a young girl sold into sexual slavery confronting the woman who she says was responsible. And the American couple who takes us on a mission to rescue underage girls trapped in a cycle of poverty and exploitation. ABC's Bob woodruff traveled to Cambodia. Reporter: At first glance, 22-year-old soka Chan might look like your average, everyday California girl. She has a lap dog named chica. And her own car that she bought herself. Behind all this, soka hides a dark past from her childhood that still haunts her to this day. I'm going to go pack. Reporter: She decides to travel 8,000 miles. Thank you so much for soka and for this opportunity to go see the family -- Reporter: To confront that past back to where her life started. Cambodia. It's a bittersweet return. Cambodia's often called the kingdom of wonder. But turn down certain side streets and you will find a sordid world. Where sex is the hot commodity. How are you? Reporter: And children are a currency. This pimp came up to me and asked me if I wanted young girls. And not only that, he took me to a house where there were 60, at least 60, young girls to choose from. Reporter: It's a reality soka lived through. At 7 years old, she was sold for sex to this man, Michael Joseph Pepe, an American former marine living as an expat in phnom penh. What did Michael have to do with you? He wanted my virginity. He's the first guy. When you were 7 years old? Yes. An American? An American man. Why did he do that? I don't know. Good question. Where can I find sex with young girls? Reporter: You're looking at hidden camera footage. Western men soliciting sex with underaged girls. How old do you want? 10. 10 years old? Okay. 8, 9, 10, 11. These were shot over the last two years. How old do you want? You know. Under 10, all of them. 10. Reporter: The video was shot by agape organization, an organization dedicated to stopping child sex trafficking in Cambodia. This makes me want to throw up. This is your people asking what age they want. Someone wanted a 10-year-old. Would have taken an 8-year-old. 8, 9, 10-year-old. Reporter: Former pastor don Brewster and his wife Bridget founded aim to protect Cambodian children from men like these. Why is it pedophiles often come to Cambodia? Because they can get away with it. They may not physically take a life but they are killing a child in the sense that childhood is gone, that will never be regained. Soka will never have a childhood like other children have had. Tell us what happened when soka was 7 years old. Yeah. She was sold. She was sold to Pepe. The virgin sale. Yeah. Reporter: For soka, that was just the beginning. She would spend about five years shuttled to different illegal brothels. Always locked in a dark room. All before her 12th birthday. In that house, if you see that room, you will know that I'm going to die in there. Because in that room is so dark. And doesn't have anything. Doesn't have the light, doesn't have the restroom, doesn't have nothing. So all that till you're 12 years old? And I cry every day. And I scared every moment. And now I still scared when I sleep at night. I don't close my eyes. When I close it, I'm so scared. I feel like someone going to come to call me, to call me out of the room. Reporter: But then when she was 12, seemingly out of nowhere, a miracle. The gate opened. And all the police came in. That's how they rescued. Reporter: Soka had been rescued by an Ngo working with don and Bridget. What was she like? She was shy, really shy and quiet. Yeah, and she had like a tic. Really, really pretty significant at the time when she first came. Reporter: That shy little girl once played on streets much like these, not knowing sexual predators were lurking nearby. Those history risk undercover videos were filmed right here. Just steps from don and Bridget's home. There's no shame. Can you imagine 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. Right around the corner there's both drug and sex traffickers. That's a dangerous part of town to go into. Reporter: Every building of their compound here was once a brothel that sold children. This was the worst brothel in a village that was brothel after brothel after brothel. This is where the young kids were. The 8, 9, 10, 11-year-old kids were housed in this building. Reporter: For children as young as 8 years old, concrete walls, colored pink, shut them off from the world. This is what the kids stayed in. Really, this is where they were forced to have sex. Yeah, I mean there was no light down here. Now it's all lit and up stuff. You know. Go out to a backyard and such. This was completely dark back here. The back door was cemented closed so they couldn't escape out the back way. Do you have any nightmares about what you lived through? Yes. Is really scary when I have nightmare. Make me want to be with someone. Reporter: For don and Bridget, they know many more girls like soka are out there alone, trapped. They needed to do more. When we come back, we take you inside the private war to rescue girls just like soka and -- soka confronts the person she says first sold her into the sex trade when she was a 7-year-old child. Does she deny that she sold you? Yes. Did she ever apologize?
This transcript has been automatically generated and may not be 100% accurate.