No doubt when Mr. Kalanick met the wide-eyed Ms. Fowler at the office Christmas party soon after she started, it never entered his head that she would become the disciplinarian who effectively confiscated his car keys for reckless driving with one blog post.

Yet it was a role that Ms. Fowler had been preparing for her whole life. The Peter Pan libertines met their match in a sweet Stoic.

She had what she calls an “unconventional upbringing,” the second child of seven in a small town in rural Arizona called Yarnell. Her father was an evangelical Assemblies of God preacher who sold pay phones on weekdays and, with his wife, home-schooled Susan and her siblings. She ended up never going to high school.

“So I was kind of on my own,” she says. “I tried to read the classics, would go to the library a lot, tried to teach myself things. But didn’t really have any direction. I really had this dream that someday I could be educated.”

She read Plutarch’s “Lives.” “The Stoics were really what changed me,” she says. “Because their whole thing was about, ‘You don’t have control over a lot of the things that determine your life, so all you can do is focus on becoming the best person that you can be.’ And that really spoke to me because I did feel, especially during my teenage years, that my life was really out of my control. I really wished that I could just learn and do all the fun things and cool extracurriculars that I thought everybody else my age was doing.”

Ms. Fowler worked as a stable hand and a nanny to help support her family. “And I would tell myself, in the times when I would be really, really sad, ‘Once I get out of here, I’m going to do something great.’ And I would just pray at night, like, ‘God, please just let me get out, give me opportunities to get out. I promise I’ll do good with it.’”

At 16, she began “freaking out” about her future. “I had this really intense resolve. I would call universities and community colleges and say, ‘I really want to go to college? How do I get to college. What do I do?’ And they would say, ‘You have to get an application. You have to get letters of recommendation.’ It was terrifying. I had no idea what I was doing.”

She figured out how to take the SAT and ACT. She made a list of all the books she had read and at the top wrote, “Susan Fowler’s Home School” and sent it off to Arizona State University.

“And they actually gave me a full scholarship,” she says, the wonder still in her voice.

The college balked at letting her take math and physics to study astronomy, given her lack of high-school prerequisites. “And I was like, ‘No! I didn’t come this far, now that I’ve found something I really loved, to have my dream smashed,’” Ms. Fowler says.

She applied to the top 10 colleges as a transfer student and was accepted at the University of Pennsylvania, where she was told she could study physics and given help with the steep tuition.

After a rough first semester, advisers tried to steer her away from physics. So she walked into the office of Penn’s president, Amy Gutmann, and left a message with her assistant: In a commencement speech, Ms. Gutmann had said that the school would help students fulfill their dreams.

“I heard back directly from the president herself, and she was like, ‘You are right. This is a place for people to fulfill their dreams.’” She told Ms. Fowler she could get back to her whiteboards, and after that, it was “fantastic.”

The essay that shook Silicon Valley was called “Reflecting on One Very, Very Strange Year at Uber,” and Ms. Fowler began by noting that it was “a strange, fascinating, and slightly horrifying story.” Published on Feb. 19, it rocked the world’s most valuable start-up, challenging the mantra that great disrupters are above the law. The blog post was notable for its dispassionate tone, as the young engineer who had left the company after a year walked the reader through everything that had gone very, very wrong in the brozilla culture of kegs, sexual coarseness and snaky competition.

Ms. Fowler was on her first day with her new engineering team when her manager sent her a string of messages over the company chat system.

“He’s telling me that he’s in an open relationship and that his girlfriend is getting laid all the time, but he just can’t because he’s at work all the time,” she says, reprising her blog post with me. “And he’s trying really hard not to get in trouble at work, but he’s really looking for a woman to have sex with. And I was like, ‘What the hell? This can’t be real. How stupid does he have to be?’ But it turned out he’d been getting away with this for so long, he didn’t care anymore. And I feel like so many of these men, they believe that the only reason women get into these jobs is to get a guy.”

Ms. Fowler took screen shots and reported the manager to human resources, thinking, “They’ll do the right thing.” But they didn’t, explaining that the manager was “a high performer” and it was his first offense, something Ms. Fowler later discovered to be untrue.

“Somehow I’m supposed to be like, ‘Oh, he’s a high performer? Never mind. How dare I?’” she says, laughing.

She wrote that H.R. told her she could either find another team to work on or stay on that man’s team and expect a poor performance review. Another manager told her that if she reported stuff to H.R., he could fire her. Amid the manic, sexist behavior, the number of female engineers in the division Ms. Fowler was part of dwindled to less than 6 percent — too few, the company said, to merit ordering them the same black leather jackets they were ordering for the men.

When Ms. Fowler earned some money from “Production-Ready Microservices,” a book on engineering she wrote, she went out to Madewell and bought herself a black leather jacket.

“I didn’t really care if they branded me a troublemaker,” she says, “because I hadn’t gotten that far in my life and overcome all these things to get treated inappropriately. I wasn’t going to take it. I’d worked so hard. I deserved so much better. And I was, like, ‘No. That’s not O.K. You don’t get to do that.’”

In her memo, she says, “I knew I had to be super-careful about how I said it if I wanted anybody to take it seriously. A lot of women have been whistle-blowers in the past, and a lot of them have just gotten torn down and treated terribly. One of the things that kept popping up was this idea that if you do whistle-blow about sexual harassment, then that is what will define the rest of your life. And I kind of struggled with this. But then, to me, I realized, you know what? No. Stepping back, just being in my little Stoicism Susan bubble, if what people know you for is bringing light to an issue about bad behavior, about bad stuff going on and laws not being followed and people being treated inappropriately, why wouldn’t I want that? That’s a badge of honor.

“And I wasn’t just standing up for myself. I felt like I was standing up for everyone else that I was seeing at Uber who was mistreated. It was an extremely demoralizing environment. I would see people who would get harassed or made fun of or bullied and they would go report it, and they would just get ground down by upper management and H.R. And so I felt like, if I can take this on despite the consequences, then I should do it.”

Like women in Hollywood I talked to after the Weinstein collapse, Ms. Fowler thought the new outspokenness in Silicon Valley on sexual harassment may have been spurred by the election of President Trump.

“The second Trump won, I felt super-powerless and I thought, ‘Oh my God, no one’s looking out for us,’” she says. “They have the House, they have the Senate, they have the White House. And so we have to take it back ourselves. We have to be the ones doing the work.”

The only woman on the board then, Arianna Huffington, who had vowed that the culture of “brilliant jerks” must end, had been trying to help Mr. Kalanick by advising him to sleep more and meditate. But he caused another kerfuffle when he chose to meditate in the lactation room.

When Ms. Fowler’s memo exploded, Ms. Huffington oversaw the investigation by Eric Holder, reached out and talked to employees, and said she wanted to “hold the leadership team’s feet to the fire.” Uber later fired 20 people, including senior executives.

“So I was disappointed in her because I expected her to be an advocate,” Ms. Fowler says, noting that Ms. Huffington appeared on TV after the blog post to insist that there’s no “systemic problem” at Uber.

“I had two friends who went to her and Liane Hornsey, who’s the head of H.R., and reported various harassment discrimination,” Ms. Fowler says. “And then I was told that many other women were doing the same thing. And then Arianna went on TV that same week and said, there’s no ‘systemic problem.’ Which I was like, ‘No, a whole bunch of people just went to you this week.’” Ms. Fowler adds that the company’s C.T.O., Thuan Pham, who knew about her complaints, is still in the same job.

Ms. Huffington told me that she agreed that the problem was “systemic sexism,” but that she did not believe there was “systemic sexual harassment.” But, she added, “there should be zero tolerance for even one case of sexual harassment.”

“I was totally supportive of having a full investigation of her claims,” Ms. Huffington says. “That’s why we brought in a former attorney general to investigate. I don’t think you can do a lot more than that.”

Ms. Fowler is not so sure. “The one interaction we had was right after I published the blog, when I started getting calls from friends and family and even acquaintances I hadn’t talked to in years and years who were getting calls about private investigators asking about it,” she says “And I was pretty sure that this was coming from Uber or someone close to Uber. So I sent an email to some of the members of the Uber board because I was like, ‘Look, I don’t know if you’re responsible for this, but hey, if you’re doing this, please stop.’

“And Arianna responded and she was like, ‘Travis has assured me that he did not do this.’ And I replied, asking her, ‘O.K., well, then, could you please go and say publicly, “Whoever’s doing this, stop,” if somebody is?’”

Ms. Huffington told me that “the board had a complete assurance from management that nothing was done like that or would be.”

Speaking to The Wall Street Journal earlier this month, Ms. Hornsey, who joined Uber a month after Ms. Fowler left and a month before the famous blog post, was asked if she had ever reached out to Ms. Fowler.

“I have said, very publicly, ‘Thank you’ to her because she raised some stuff that did lead to change,” she said. “I don’t know whether there would be any benefit in meeting her. I’m seriously working for my employees today; she’s an ex-employee.”

Ms. Fowler tweeted a screen shot of that part of the interview, saying: “Oooh burn” and “She really, really doesn’t like me.”

On the advice of a friend, Ms. Fowler got private security for the first few weeks after she published her incendiary essay.

She thinks Silicon Valley needs to get rid of forced arbitration. “When you join these companies, they make you sign away your constitutional right to sue,” she says.

Ms. Fowler has taken that to the Supreme Court, and as is her wont, is studying the syllabuses of Columbia Law School so she can learn more about her rights.

She now has a job at Stripe as the editor of its tech publication. And she’s working with Verve, a Hollywood talent agency, developing a movie based on her experiences, described by the agency to me as “Erin Brockovich” meets “The Social Network.”

Meanwhile, Ms. Fowler is still reading the Stoics (while Mr. Kalanick is still wrestling with the board about who should control the company he started). “I think, right now especially, with Trump in the White House, who knows what’s going on with North Korea? Then we have natural disasters happening. It just feels like you’re being tossed around on the ocean and there’s nothing. What I keep going back to and what keeps me going, is trying to do good in whatever little spot of the world we can influence, no matter how small.”

As we leave, I ask Ms. Fowler if she knows the baby’s sex.

“A girl,” she says, smiling radiantly. “I’m so excited. Now I’m just like, ‘Got to make this world better so she doesn’t have to deal with these things.’”

Susan Fowler submits to a round of Confirm or Deny, here.