Transcript for Former NXIVM member says she was branded when invited to secret sorority
Reporter: We are told the rendezvous was a secret. Five women summoned to a house outside Albany New York, one night this past March. Sarah Edmondson says she was one of them, willingly participating in a strange initiation ritual led by a woman who told everyone to take off their clothes and put on a blindfold. Led us in blindfolded and sat us in a semicircle buck naked, no clothes, on a sheepskin rug. Reporter: Edmondson told authorities she thought they were going to get tattoos. Instead, she says, they found out they were all going to be branded. What was that like? It was worse than childbirth. Imagine a hot laser dragged across your flesh for 30 minutes without anesthetic. Reporter: At this point, you're probably wondering how in the world did this happen? Sarah seems so Normal. She lives in Vancouver where she is a wife and mother with a successful film and television career. Do I know you? I don't think so. No, no, I never forget a face. Reporter: Her life changed after she crossed paths with a secretive self-help group nxium and its charismatic leader Keith Ranieri. I'm an interesting person, I'm a controversial person, most importantly an unconventional person. Reporter: According to promotional materials, even as a child Ranieri was destined for greatness. Speaking in full sentences at age 1, reading at age 2, judo champ and concert-level pianist at 13. I was told he was one of the smartest men in the world, just an incredible man. With that I'm going to pass the microphone over to Mr. Ranie Ranieri. Reporter: So incredible, it seems, an honor name won't do. Participants say they're taught to camemera theory vanguard. Vanguard, because he's the leader of a philosophical movement. Reporter: At the heart of Nexium training is intensives which former members say are like group therapy. Running as long as 14 hours a day and up to 16 days. Edmondson says she attended her first one in 2005. She says it cost over $2,000. I left my five day, my initial training, as if a veil had been lifted and I could see things more clearly in my life. Reporter: In promotional materials and videos Nexium claims more than 16,000 people worldwide have taken its courses. But participants are required to sign a confidentiality agreement. So what do we actually know about this secretive self-help group? According to former members, Nexium has its own lingo. And the sessions came to involve practices such as chanting. A special handshake. Even bowing. To vanguard. Thank you, vanguard. Reporter: Former members, like mark Vicente, say anyone unwilling to go along with the rituals would be scorned. If you questioned Keith Ranieri, the Hits the fan. Like what? You are prideful. How dare you. Don't you realize you owe everything to him. Reporter: Before he founded Nexium, Ranieri's first big idea came in the 1990s, hawking memberships in an ill-fated networking marketing company. His name is Keith Ranieri, his product is consumers byline. Reporter: Consumers buyline featured Eddie alvers of "Green acres" fame and an awkward Ranieri, pitchman. Good to see you. Good to see you. It's an amazing idea. Sometimes it even amazes me. But consumers byline is wonderful and it's working. It really was a brilliant idea, based on the premise of as a group collectively, we can buy in bulk, we can save a lot of money. Reporter: Tony Natali knew Ranieri before he was vanguard. When you met him did he seem like a genius? He seemed like a geek. I asked him, you have a 240 iq, why are you doing this? He said, this is the platform that I'm going to use, and I'm going to change the world. Reporter: But not everyone was buying what Ranieri was selling. Attorneys general in several states began looking into consumers buyline's practices. We told you about consumers buyline last may when the company was accused of being an illegal pyramid scheme -- Reporter: The company settled without admitting wrongdoing but agreed to pay hundreds of thousands of dollars to the states. After that, the company went bust. By that time, Tony Natali was all-in. She had left her husband and moved to Albany with her young son to be with Keith. They were together for nearly six years. Here's the smartest man in the world willing to help you through your emotional issues. Help you heal sexually, help you heal intellectually, you just have to trust me. Reporter: She witnessed the early days of Nexium. Ranieri had partnered with a woman named Nancy Saltzman, and together they created teachings known as rational inquiry and methods that in court filings Natali later likened to brainwashing. He elicits all that information from you. My opinion is that what they do from there is they take that information and they utilize that. Where can I not build you up but break you down? Reporter: Over time, Natali says her relationship with Ranieri changed. He started to get aggressive, controlling, and worse. When I no longer wanted to have relationships with him any longer, he would force me, he would rape me. Reporter: In a court filing she alleged that Nexium was a cult, presided over by Ranieri, and that he raped her repeatedly. In their filings, Nexium lawyers say Natali's allegations are false, they call them scurrilous, scandalous, slanderous. Sarah says when she was involved in Nexium, Ranieri taught women were to be subservient to men, and he practiced and he preached by having what amounts to a harem of women. I've spoken to five different women in the harem. It was like having a Normal boyfriend except you wouldn't know when you'd see him next. He'd go off with another woman the next day. How does he do it? To be honest, he looks like a schlub. Right. My personal belief is that it's one gigantic hypnotic induction. I think that there's a certain percentage of people that are susceptible. Reporter: In fact, his followers are so devoted that they travel in from all over the world to celebrate Ranieri's birthday. An annual celebration known as vanguard week. Wishing vanguard a happy birthday. I loved v-we cek. My favorite time of year. I missed my best friend's wedding. It was more important to be at v-week. I missed her wedding. You were deep in. I was deep in. Reporter: She was in the group 12 years, rising through the ranks. During that time she says she got close to Nancy Saltsman's daughter Lauren, who was her maid of honor. She's like my therapist. In the ranking system she's above me. Reporter: In March, after all their years together in Nexium, Sarah says Lauren approached her about a new and mysterious opportunity. Life-changing, but top secret. Reporter: But Edmondson claims Lauren Saltsman demanded highly compromising collateral first. In response she says she and some others ended up providing nude photos of themselves. Instantly all my alarm bells are going off. Absolutely. Why did you do it? Because I trusted her. Reporter: Only then did she gain entry. And the first step is making a vow of obedience to her, as me being a slave, her being my master. Slave? She used the word slave? She used the word slave. Did you object? Of course, every stage of the way. She said, it's a metaphor, it's a guru/disciple. Reporter: All of which led to the night she and other women submitted to being branded by this woman she says, Danielle Roberts. The woman on the table screamed out in pain, twisted and turned and yelled and the woman I was with holding her legs down, we looked at each other and wept. Why didn't you let go and run out of there, even naked? It didn't seem like a choice at the time. Could you stand up and point where the brand is? So it's right here. Right under my underwehrlein. Reporter: An attorney for Dr. Danielle Roberts tells ABC news the allegations are unfounded. But Edmondson did file a complaint on Dr. Roberts with the New York department of health. In response the agency said the issue she described are not medical misconduct. Edmondson believes Ranieri should also be held accountable because she says she saw a text come in from him as she held Lauren satsman's phone, filming the branding. When we were doing the branding, a text came through from Keith. And it said, how are they all doing with each other? So he knew. He knew. He knew we were all being branded. Reporter: Ranieri did not respond to requests for an interview, but in a letter posted on the group's website says "There is no merit to the allegations we are abusing, coercing, or harming individuals." Ranieri says that secret sorority is not part of Nexium and "I'm not associated with the group." The letter also says "Our experts say members of the sorority are thriving, healthy, happy, better off, and haven't been coerced." But in Edmondson's complaint she says she was told that the brand was a Latin symbol. Later she says she realized it included the initials of Nexium's leader and those of a fellow actress. The four elements were Keith's initials from one side, "A.M." For Alison Mack from dead on. I didn't see that at the time. Reporter: Coming up, vanguard goes Hollywood. Why are so many young actors following the guru of Albany? Why do you think -- So emotional for me? Yes. Reporter: One star's fight to get her daughter back. She's in danger, in my opinion. She's in grave danger. Reporter: Stay with us. Cally. ???
This transcript has been automatically generated and may not be 100% accurate.