Transcript for Gretchen Carlson's Sexual Harassment Claims Against Ailes: Part 1
A media and political bombshell. Reporter: It was a spellbinding summer surprise. Major change at Fox News. CEO Roger Ailes has handed in his resignation. Reporter: A lawsuit that helped bring down a titan of television. Roger Ailes, the founder and force behind Fox News, accused of sexually harassing one of his network's on-air stars. On what Richter scale was the earthquake that Gretchen Carlson started by filing this lawsuit against Roger Ailes? It was off the charts. I mean, nothing like that had ever really happened at Fox News before. Reporter: Sarah Ellison has reported extensively for "Vanity fair" on Fox News and the legend of Roger Ailes. He takes a lot of credit, and deserves a lot of credit for creating the success of fox News. And you could see that, when you look at the channel, you're looking at his vision. So, can a 4-year-old be a pinhead? Reporter: A vision that included a signature hook. Fair and balanced. Reporter: And, some say, a signature look. Which you could spot the minute you turned it on. When I turn from NBC to CNN to fox, you can tell the difference. The dresses are tighter, and the skirts are shorter. The sort of famous leg cam, which is a camera that sort of shoots at a particular angle so that you can see that her legs are crossed, and her thigh is sort of revealed. Reporter: Belinda Luscombe wrote a cover story about Gretchen Carlson for "Time" magazine. Gretchen joked about this when she went on to a radio show and she got to wear jeans. And she said, "It's so great to be on radio because I can wear pants for a change." Reporter: In her skirts and dresses, Carlson was on the set of the popular morning show "Fox and friends," where she was co-anchor for seven years. Good morning, everyone. Reporter: In her lawsuit against Ailes, Carlson alleged that behind the sunny morning show exterior was a hostile workplace, more reminiscent of a locker room than a newsroom. You read the headlines. Reporter: She names her co-anchor, Steve Doocy. Yes. Reporter: In the lawsuit. Yes, I mean, she talks about how he demeaned her. He pulled her arm to get her to be quiet in various moments. Reporter: She did go to Roger Ailes to complain about the behavior of her co-host on "Fox and friends." He was not a sympathetic ear. No, instead of having Roger Ailes say, "Oh, we'll be sure to do something about that," he lashes out at her. And he calls her a man-hater, and he says that she should try to get along with the boys. Reporter: Carlson claims that shortly after she complained, Ailes demoted her, moving her off the morning show to a less desirable time slot in the afternoon. Hi, everyone. I'm Gretchen Carlson, and this is the real story. Reporter: But it gets worse. In Carlson's complaint, she says Ailes then began sexually harassing her. Making comments in one-on-one meetings like, "I think you and I should have had a sexual relationship a long time ago." Adding that, "Sometimes problems are easier to solve" that way. When she rejected his advances, Carlson says Ailes retaliated, sabotaging her career. But Gretchen Carlson wasn't about to fade away without a fight. A lot of the people I interviewed about Gretchen thought, "Well, Gretchen is somebody who always does her homework. She's super prepared. So she would not have launched this without having the goods." She starts to tape her meetings with Roger. And it's at this point where he sort of begins to say things to her that she includes in a lawsuit later. Reporter: The man who ruled Fox News like an empire, who even had a camera trained outside his office to see who was approaching, was walking into a trap. It is ironic that here's this person who's so famously paranoid about people trying to get him, who then is -- Reporter: Brought down by -- Having someone just record him very simply with her iPhone. Reporter: Last June, with Carlson still quietly gathering evidence, Ailes abruptly fired her. Two weeks later, she shot back with her explosive lawsuit. Fox News' dirty laundry was now its own top story. Fox News chairman Roger Ailes is responding to a lawsuit filed by lawyers for Gretchen Carlson. Reporter: What was the initial reaction toward Gretchen? I mean, it was horrendous. One personality after another came out and said, "It doesn't sound true to me. I've -- Roger's never said anything like that around me. So what do you think when you heard this? I've worked for Roger for 20 years. Best boss I've ever had. I stand behind Roger 100%. Reporter: Along with bill O'Reilly, Geraldo Rivera, Greta van susteren, Sean hannity, all lined up to back the boss. And Fox News' Brit Hume tweeted, "Why didn't she quit and sue instead of suing only after she got fired?" If you speak up when you're first hired, you're considered a troublemaker. If you speak up when you leave, it's considered sour grapes. Reporter: As soon as Carlson filed her lawsuit against Ailes, Fox News parent company 21st century fox launched an internal investigation. I think from that moment forward, the die was cast. I mean, they kind of knew that if you went digging you were going to find something. Reporter: And what the law firm conducting the investigation found was at least a dozen women willing to talk. Some of whom had strikingly similar stories about Roger Ailes. It gave the story a level of credence that it wasn't just Gretchen Carlson. There were other women. Reporter: The crisis came to a crescendo when one woman, who was noticeably absent from the Ailes chorus of defenders, spoke up. Megyn Kelly. The highest-profile female anchor at Fox News had also been allegedly harassed by Roger Ailes. Reporter: Just this week, Megyn Kelly appeared on "Good morning America," describing in detail what she says happened to her. It culminated in a physical attempt to be with me. Which I rejected, in his office. And then I contacted a lawyer. He touched you? He tried to kiss me three times. So I rejected that. And when I rejected that, he asked me when my contract was up. It's a fantastic deconstruction of the myth that only shy little violets get harassed. Only weak women who aren't in power get harassed. Women deal with it all the time. Reporter: Everywhere. In every industry, everywhere. Reporter: Kelly's claims would spell the end for Roger Ailes at Fox News, but it all started with Gretchen Carlson. If Gretchen Carlson hadn't sued, would Roger Ailes still be the chairman of Fox News? I think so. I think so. Reporter: But just two weeks after she filed her lawsuit, Ailes arrived at work to find he had been locked out of the company he created. The next day it was announced he was resigning as chief executive. In September, 21st century fox settled with Gretchen Carlson, agreeing to pay her a staggering $20 million and offering a rare public apology. Saying, "We sincerely regret that Gretchen was not treated with the respect and dignity that she and all of our colleagues deserve." Women do not normally get an apology when something like this happens. And I think that that was extraordinarily important. Reporter: Roger Ailes has vehemently denied all of the allegations of sexual assault against him. But in perhaps the truest testament to the herculean feat Carlson accomplished, some of those familiar fox faces who supported Ailes have now offered her an apology. I don't think it's overstating it to say that Gretchen Carlson toppled an empire.
This transcript has been automatically generated and may not be 100% accurate.