Great crises in American political life often produce a new hero, someone whose courage and charisma capture the imagination of the decent half of the country.

In the 1950s, when Joe McCarthy terrorized America with wild claims of communists lurking in every army barracks and state department corridor, it was an attorney, Joseph Walsh, who demanded of the Wisconsin senator: “At long last, sir, have you no sense of decency?”

Twenty years later, when the country was transfixed by the Watergate hearings, it was a folksy senator from North Carolina, a first world war veteran named Sam Ervin, who won hearts with sayings like: “There is nothing in the constitution that authorizes or makes it the official duty of a president to have anything to do with criminal activities.”

Forty years on, after Donald Trump entered the White House mining what Adam Schiff calls “a dangerous vein of autocratic thought” in the Republican party, the then little-known California Democrat did more than anyone else to unravel and excoriate the high crimes of a charlatan destined to be the only president twice impeached.

During the pandemic, Schiff used his confinement to write a memoir which offers a beguiling mix of the personal and political. The book, Midnight in Washington, is full of new details about investigations of the president’s treason and how the House speaker, Nancy Pelosi, and the rest of the Democratic caucus decided impeachment was necessary.

But the human side of the story is the most compelling part: the history of Schiff’s Jewish-immigrant ancestors, the sustenance he received from a brilliant wife and a devoted son and daughter, a career path that made him the perfect person to meet his moment in history.

“I enjoyed writing the first part of the book the most,” Schiff said. “In so many ways I feel like the life I had before Trump prepared me for the national trial that was to come.

“The prosecution of an FBI agent for spying for the Russians. Living in eastern Europe and watching the rise of an autocrat in Czechoslovakia literally tear the country apart. And my own family’s history in eastern Europe. All of these things seemed to prepare me without knowing it for the rise of a xenophobic autocrat in our own country.”

In choppy political waters, a brilliant spouse is a great advantage – especially one who sometimes knows you better than you know yourself. When the Democratic establishment recruited him to run for Congress, after he was elected to the California senate, Schiff thought he was undecided. His wife, Eve, knew otherwise.

“You’re going to do it,” she said, after he came back from meetings in Washington.

“I don’t know,” he replied.

“Yes, you do,” said Eve. “You’re going to do it.”

She was right.

Schiff’s love of bipartisanship, which ended with the Trump presidency, was inherited from his father, a “yellow dog Democrat” (a person who would vote for a yellow dog before he would vote Republican) and his Republican mother.

His father offered him advice that has served him all his life: “As long as you are good at what you do, there will always be a demand for you.”

“This was a very liberating idea,” Schiff writes, “that all I needed to do was focus on being good at my chosen profession and the rest would take care of itself.”

His work as a federal prosecutor who got the conviction of the first FBI agent accused of spying for Russia was crucial to his understanding of how thoroughly Trump was manipulated by the Russians. He understood that Michael Cohen’s efforts during the campaign to close a deal to build a Trump Tower in Moscow would make Trump vulnerable to blackmail if his lawyer’s calls had been recorded. And he was astonished when he realized that that kind of kompromat wouldn’t even be necessary.

When Trump “did become president, there would be no need for the Kremlin to blackmail him into betraying America’s interests,” Schiff writes. “To a remarkable degree, he would prove more than willing to do that on his own.”

There’s lots more in the book, from Schiff’s unsuccessful effort to convince New York Times editors to remind readers the emails they were publishing to undermine Hillary Clinton had been stolen by the Russians for that very purpose, to Schiff’s revelation that if he had known how poorly Robert Mueller would perform as a witness after he completed his stint as special counsel, he would not have demanded his testimony.

“I haven’t said this before this book,” he told the Guardian. “That was one of the difficult sections of the book to write because I have such reverence for Mueller. I wanted to be respectful but accurate.”

Schiff is still at the center of political events. He sits on the House select committee investigating the deadly Capitol attack – and dealing with Trump’s obstruction.

On the page, he also recalls a hearing in 2017 when he asked representatives of Facebook, Twitter and YouTube if their “algorithms were having the effect of balkanizing the public and deepening the divisions in our society”.

Facebook’s general counsel pretended: “The data on this is actually quite mixed.”

“Maybe that was so,” Schiff writes, “but it didn’t seem very mixed to me.”

Asked if he thought this week’s testimony from the Facebook whistleblower Frances Haugen would create enough pressure to pass new laws regulating social media platforms, Schiff said: “The answer is yes.

“I think we need regulation to protect people’s private data. I think we need to narrow the scope of the safe harbor these companies enjoy if they don’t moderate their contents and continue to amplify anger and hate. I think we need to insist on a vehicle for more transparency so we understand the data better.”

But then he cautioned: “If you bet against Congress, you win 90% of the time.”

‘Eureka moment’

On the page, Schiff records an airport exchange with a Republican stranger, who said: “You can tell me – there’s nothing to this ‘collusion stuff’, is there?”

It is a conversation which should put that question permanently to rest.

Schiff said: “What if I was to tell you that we had evidence in black and white that the Russians approached the Clinton campaign and offered dirt on Donald Trump, then met secretly with Chelsea Clinton, John Podesta and Robby Mook in the Brooklyn headquarters of the campaign … then Hillary lied about it to cover it up. Would you call that collusion?

“Now what If I also told you that after the election, former national security adviser Susan Rice secretly talked with the Russian ambassador in an effort to undermine US sanctions on Russia after they interfered to help Hillary win. Would you call that collusion?”

The Republican was convinced: “You know, I probably would.”

For Schiff, it was a “eureka moment”.

“Now,” he thought, “if I can only speak to a couple hundred million people.”

Schiff’s book should convince a few million more that everything he said about Trump was true – and that the country was exceptionally lucky to have him ready and willing to defend the tattered concept of “truth”.

• Midnight in Washington is published by Random House