The book’s title is What Happened, but Clinton could easily have called it, What Might Have Been. What might have been if she hadn’t used a personal email account and private server as secretary of state, or if the media had not spent so much time covering it? What might have been if Clinton hadn’t given paid speeches to Wall Street bankers—“a mistake,” she begrudgingly acknowledges? What might have been if Sanders had not “caused lasting damage” with his attacks during the primary that, she writes, paved “the way for Trump’s ‘Crooked Hillary’ campaign in the fall?” What might have been if former FBI Director James Comey had not called her handling of classified information “extremely careless” or, more consequentially, not sent his infamous letter to Congress 11 days before the election? What might have been if President Obama had ignored the threats of Republican leaders and more forcefully warned voters about Russia’s attempt to influence the election?

Clinton addresses all of these possibilities, and she concludes, as many observers have, that she was defeated by “a perfect storm”—a confluence of errors (some her own) and unlikely factors that turned an exceedingly close election against her. Had any one of them not happened, she suggests, it might have been enough to swing the 40,000 or so votes in Wisconsin, Michigan, and Pennsylvania that ultimately made the difference.

Yet another, often unstated theme of the book is that Clinton was done in by presumption, by decisions that she and other actors in the campaign—Comey in particular, as well as Obama—made because they presumed that she would become president whether they were taken or not.

No longer a candidate or a potential candidate, Clinton writes that she is “letting my guard down.” And indeed she does. The first woman presidential nominee of a major party writes extensively about the role that sexism played in the campaign in her defeat, as well as how it continues to shape the lives and perceptions of women in public life and in the workplace. She goes into more detail than ever before about the time, energy, and resources she and others would spend on hair and makeup during the campaign—an effort that only female candidates must make, and one that they dare not discuss for fear of appearing out of touch.

Clinton is also unguarded in describing the many ways in which she assumed she would win. That was not entirely the case before the campaign, when she and Bill Clinton considered the historic difficulty of one party holding the White House for three consecutive terms. But the presumption took hold once it became clear she would be facing Trump, a candidate who Clinton, like so many others, did not take seriously at the start. While Clinton spent weeks sweating the details of her victory speech, she didn’t so much as look at a concession speech until her aides handed her a draft in the wee hours of November 9. “I hadn’t prepared mentally for this at all,” she writes about election night. “There had been no doomsday scenarios playing out in my head in the final days, no imagining what I might say if I lost.”