A Higher Loyalty, by far the most consequential book yet in the literature of the Trump presidency, is arriving as political conflict roils every aspect of that presidency. Former FBI Director James Comey's scathing review will not settle the arguments about President Trump, nor will it calm the controversy over its author. But it will furnish mountains of ammunition for combatants on all sides.

Comey fires countless fusillades against the president who fired him in May 2017, summing up at the end: "[T]his president is unethical, and untethered to truth and institutional values." Trump's leadership, Comey says, is "transactional, ego driven and about personal loyalty."

He compares Trump's insistence on a "silent circle of assent" to the code observed in the Mafia crime family that Comey helped bust as a young prosecutor in New York City.

Loyalty was, on one level, the issue over which Comey supposedly was fired. Comey details his conversations with Trump in the early weeks of 2017, noting how often Trump tried to isolate Comey one-on-one and elicit a pledge of loyalty.

Comey says he offered his "honest loyalty" instead. At first, it seemed enough. Comey told the president he was not being investigated with respect to certain allegations made in the so-called Steele dossier, a raw file compiled by an ex-British spy and shared with the FBI (later published by BuzzFeed News).

But the president returned to the subject repeatedly, Comey reports, asking him to "lift the cloud" and corroborate the presidential denials of various sexual accusations. He wanted Comey to consider "letting this go" after Trump's first national security adviser, Michael Flynn, was forced to resign after misrepresenting to Vice President Pence conversations he'd had during the presidential transition with Russia's ambassador. (Flynn would later plead guilty to lying to the FBI about contacts with the Russians.)

Then Comey's relationship with the president cooled further after Comey took exception to Trump saying that Russian President Vladimir Putin might be a killer, but the U.S. "is not so innocent."

In this relatively short book (due to be published April 17, although NPR obtained an advance copy), Comey presents Trump as a man who never laughs, a man who sizes up other people as assets or targets and — above all — a man who is "without respect for truth."

Such denunciations will have some readers cheering, but they will also fuel the narrative that has arisen in conservative circles and in much of the right-leaning media in the run-up to A Higher Loyalty's publication. In this view, Comey is an ego-driven false martyr, not only bitter and vengeful but downright corrupt — a sellout to the Democrats who have refused to accept their loss or Trump's triumph in 2016.

Some of this has become remarkably vituperative, assuming the tone of Trump's own attacks on Twitter. On Fox News this week, lawyer and Fox News contributor Joseph diGenova referred to Comey as "the dirtiest cop in America."

It would be hard to imagine a characterization further from the self-portrait Comey draws in his memoir, tracing the development of his career and his character from high school through years as a prosecutor, deputy attorney general, private lawyer, law professor and FBI director. He maintains an air of rather self-conscious rectitude throughout, while finding much to disapprove of in the world around him.

"Lying about things, large and small, in service to some warped code of loyalty. These rules and standards were hallmarks of the Mafia, but throughout my career I'd be surprised how often I'd find them applied outside of it," Comey writes.

Even when working for major figures such as New York prosecutor (and later mayor) Rudy Giuliani, President George W. Bush or Vice President Dick Cheney, Comey begins with an air of respect but develops doubts and criticism as he discovers their feet of clay.

Self-critical at times, high-minded throughout, Comey holds himself to a superior standard. "Anyone claiming to write a book about ethical leadership can come across as presumptuous, even sanctimonious," he writes. Yes, the reader might concur, especially if the writer quotes theologians like Reinhold Niebuhr as often as Comey does.

Comey, who stands 6 feet 8 inches, confesses to lying about a college basketball career. Knee surgery curtailed his playing days, but as a young man he would sometimes let people think otherwise. Later, he wrote to associates to make clear he had not played college ball. The important thing was not to allow a lie to live on, to grow, to become a habit.

At this point, the memoirist has the benefit of making his case with the shining moments in his personal story. And Comey has several to touch upon, notably his refusal to let Cheney and White House staffer David Addington expand a counterterrorism surveillance program code-named Stellar Wind in 2004. Comey went to the hospital room of Attorney General John Ashcroft to make sure he did not sign off on the Cheney-Addington plan. Comey takes care to mention that he brought with him the FBI director at the time, a man named Robert Mueller.

Comey also relates his role in some of the other moral crises of the George W. Bush administration, including the treatment of Iraqi prisoners at Abu Ghraib and at various "black sites" where suspected terrorists were tortured.

But it was the Cheney-Addington showdown that established Comey's independence in the minds of many in Washington, D.C. It also appears to have impressed the man who would become the next president, Barack Obama. In 2013, Obama would tap Comey to be Mueller's successor at the FBI.

Given all this, it is mildly surprising that Comey's tell-all book withholds judgment on Trump's early presidency as a question of law. "I have one perspective on the behavior I saw, which while disturbing and violating basic norms of ethical leadership, may fall short of being illegal."

This is somewhat reminiscent of the way Comey balked at the brink of indicting Hillary Clinton in her email controversy in 2016, saying she had been "extremely careless" about handling emails that may have been classified, but that no prosecutor would take the case to court. In his book, he ruminates on this decision, and on his October announcement of a partial and temporary reopening of the email investigation just before the election.

He admits that he did it in part to dispel rumors, including within the FBI, that he was suppressing new evidence. He thought he needed to do it to prevent any cloud over Clinton's widely expected victory on Election Day.

In a remarkable look back, Comey says he was deciding "in an environment where Hillary Clinton was sure to be the next president." So any thought of concealment on his part "bore greater weight than it would have if the election had appeared closer or if Donald Trump were ahead in all the polls."

Here Comey adds: "But I don't know."

And neither does anyone else, although Clinton herself has pointed to these Comey actions as the cause of her defeat.

Now, as Comey's book appears, both he and Clinton are private citizens, speaking of their careers in past tense. Mueller, however, has re-emerged at the center of the Trump legal drama — the special counsel named by the Justice Department to continue the investigation of Russian interference in the 2016 election begun under Comey.

That investigation has been gathering momentum in recent weeks, especially with the stunning search of the hotel room and office of Trump's personal attorney in New York this week. That timing may be good for Comey's sales, but not good for Mueller's investigation.

It is far from clear what effect Comey's book will have on public attitudes toward Mueller's work. It may be equally hard to assess what impact it will have on attitudes toward Comey or Trump.

But it is not likely to convert the committed partisans on either side, or in either party. Instead, it may well cause further entrenchment, with both sides burrowing deeper into their respective certainties.

Correction: April 13, 2018 12:00 am — A previous version of this story omitted the first "and" in the following quote: "[T]his president is unethical, and untethered to truth and institutional values."

Copyright NPR 2020.