There’s a scene in Liz Cheney’s new memoir, “Oath and Honor,” when she was still in Congress, she walks through the Capitol and into the Republican cloakroom, enters a phone booth, closes the door and calls Mitch McConnell.

There aren’t so many people who can just call up Mr. McConnell nor was this quite standard procedure on Capitol Hill but, as she writes, “I had known Mitch McConnell for decades.”

In 2023, a lot separates Ms. Cheney from the average Republican politician. But reading her memoir, it’s clear how unusual her position was in late 2020 — a true insider who was also listening to and believing what was going on with Donald Trump and the conservative base. That combination seems to have inspired her turning every key available to stave off Mr. Trump’s efforts to subvert the outcome of the election, and inspired her overpowering anger toward Kevin McCarthy.

This is someone who knows Secret Service agents personally, who texted late at night with Paul Ryan about the state of Mike Pence’s mind, whose husband, Philip Perry, is so well acquainted with the former acting U.S. Attorney General Jeff Rosen that when Mr. Rosen was fending off Jeff Clark’s deranged postelection plans at the Justice Department, he called to tell Ms. Cheney and Mr. Perry that Mr. Trump might fire him.

How many people besides Ms. Cheney could help organize the writing of a letter emphasizing the importance of a peaceful transfer of power that was signed by every living defense secretary and published on Jan. 3, 2021? And how many people could listen as their father called up Donald Rumsfeld on New Year’s Eve and personally read the letter?

Unlike a number of people at similar elevations of Republican power, however, she’s never thought Mr. Trump would just fade away. That was clear in 2021. And while she’s now writing with the benefit of hindsight, part of the reason she clearly understood Mr. Trump was she was actually listening to people at different levels of Republican politics in 2020 — a secondary kind of awareness.

In her role as conference chair, she heard from members about all manner of things related to Mr. Trump, including Mike Johnson’s efforts to whip signatures for the amicus brief that challenged states’ ability to oversee their own elections. She sat in her kitchen on Dec. 12, 2020, watching a pro-Trump rally in Washington, then played back clips for her husband, who said, “It sounds like they’re advocating the violent overthrow of the government.” She writes repeatedly of exchanges with constituents and donors in the months leading up to Jan. 6, in which people described conspiracy theories.

This kind of enterprising spirit brought about her decision to call Mr. McConnell. Before reaching him, she had dialed into a conference call for Trump supporters, to hear what was up. According to Ms. Cheney, who appears to be describing a call not previously reported, a Trump adviser described the alternate elector scheme during that call. Afterward, alarmed, Ms. Cheney writes that she quizzed the House parliamentarian about what would happen if Mr. Pence decided to not count the votes. Alarmed by his answers, she next called Mr. McConnell, who told her to talk to his chief of staff and the Senate parliamentarian. That was Jan. 4, 2021.

Now that part of it ended fine — Mr. Pence counted the votes. But the whole scene underlines how fragile and chancy things became and, at times, remain: Liz Cheney in a phone booth calling up Mitch McConnell because nobody’s quite sure what will happen if the vice president doesn’t count the electoral votes.

There’s an echo here in McKay Coppins’s recent biography of Mitt Romney in which he recounts Mr. Romney and other senators asking the police where they should go next while fleeing the mob under the Capitol on Jan. 6. “The senators know,” one of the officers replied. One of Mr. Romney’s aides had to tell him, “These are the senators”!

Since Jan. 6, Ms. Cheney has emphasized the way that institutions require the people within them to actively make choices rather than passively accept events. Good norms and procedures are meant to guide people toward moral and responsible actions, so no one individual is required to act with any particular heroism.

When and how exactly to oppose Mr. Trump has, even for the small group of conservatives who want to do it, never been entirely obvious, though. Politics can lean toward inaction; action requires a choice. Mr. Coppins relays a story in his book about Beth Myers, who had worked for Mr. Romney for decades, and whose husband died suddenly around the time of Mr. Romney’s election to the Senate. She wanted to persuade Mr. Romney to resist starting his Senate career in the passive background, and instead to challenge Mr. Trump. “I’ve been in a fog the last month,” Ms. Myers wrote to him in an email, “but the desire for sane leadership from you was expressed by so many of the people who’ve been in contact with me.”

The cost of opposing Mr. Trump, or even being perceived as opposing him, increased over the years. This is clearest with the people who, through no fault of their own, end up falling unto the breach with Mr. Trump, like the election officials and workers in Georgia and Arizona who became the subjects of threats and conspiracy theories. A Georgia poll worker, Ruby Freeman, became afraid of sharing her own name. It’s often true, too, for the otherwise anonymous people who volunteer to explain how things really were with Mr. Trump. To read the committee interview transcripts with Cassidy Hutchinson is to feel how isolated her life became.

But even for the people like Mr. Romney and Ms. Cheney, who possess financial and political resources beyond those of many, their lives, according to these accounts, are now sometimes filled with panicked calls to and from family members about security.

Far beyond losing the kind of power that Ms. Cheney gave up — seemingly to prove how worthless it was compared with establishing a real record of what happened on Jan. 6 — some people who have opposed Mr. Trump have absorbed costs to their quality of life. We live in a dangerous world, fragile and chancy. The deluded man who hit Paul Pelosi in the head with a hammer managed to enter the Pelosis’ home possibly only because House Speaker Nancy Pelosi’s full-time security detail was with her, in Washington. There are millions of seams in life; thinking about reinforcing all of them would drive a person crazy.

On Jan. 6, watching TV, Dick Cheney, the former vice president, called his daughter and asked if she was watching Mr. Trump speak at the Ellipse. He then told her that Mr. Trump had said it was time to get rid of the Liz Cheneys of the world.

“You are in danger,” he warned her. Ms. Cheney is, correctly, concerned about who will and will not be there, if Mr. Trump regains power, to cut off his worst impulses and preserve the structure of constitutional government.