A hike is Michael Lewis’s interview format of choice. When he first met the FTX founder Sam Bankman-Fried in late 2021, he took the cargo-shorted chief executive on a walk through the eucalyptus trees near his Berkeley, Calif., home.

According to Mr. Lewis, Mr. Bankman-Fried huffed and puffed on the normally leisurely stroll. Hearing the young billionaire talk about his cryptocurrency exchange and effective altruism, Mr. Lewis’s “jaw was on the ground,” he said. Mr. Bankman-Fried, who co-founded the crypto hedge fund Alameda along with FTX, was throwing around numbers that shocked Mr. Lewis, describing the purported value of his exchange (he said it would take $100 billion to buy him out) and the size of the crypto market at the time (more than $2 trillion).

“That was news to me,” said Mr. Lewis, who hadn’t been following crypto closely. He asked if he could follow Mr. Bankman-Fried around and observe his life. “He kind of blinked and went, OK,” Mr. Lewis said.

Mr. Lewis was telling me this on the same hiking path, nearly two years later, in the lead-up to the publication of his new book, “Going Infinite: The Rise and Fall of a New Tycoon.” The close study of Mr. Bankman-Fried hit bookstores on Tuesday, the first day of his trial in New York City on federal fraud charges.

At one point, I looked up and saw a sign with the trail name, Wildcat Gorge. It sounded like some kind of pitfall for speculators — one of those almost too-perfect details out of a Michael Lewis book.

As it turned out, my Lewis/Bankman-Fried Hike Simulator experience wasn’t an exclusive. Mr. Lewis knows the importance of a good scene. During book promotion, he took reporters from “60 Minutes” and The Guardian on the same trail to talk about his first meeting with Mr. Bankman-Fried. (The much-hiked hike also features in a 2011 New York magazine profile of Mr. Lewis.)

Mr. Lewis was wearing a fanny pack and dark gray Hokas, one of a dozen pairs he owns from the shoe brand. “You ought to go ahead — what we’re talking about is classified,” he said with a wink as a couple of hikers passed us, and they laughed politely.

The new book arrives at a complicated moment for Mr. Lewis. “Going Infinite” is the first he has written since his daughter Dixie died in a car crash in 2021. The book is dedicated to her.

In August, Michael Oher, a Black football player whose rise Mr. Lewis chronicled in 2006’s “The Blind Side: Evolution of a Game,” filed a legal claim against the Tuohys, a white family that had taken him in. As portrayed in Mr. Lewis’s book, the Tuohys pulled a poor, underachieving teenager out of the “ghetto” to live with them, paid for his tuition at the fancy high school where he played offensive lineman and set him up to be so successful that he was recruited by the University of Mississippi — which happened to be the Tuohys’ alma mater. (And the father, Sean Tuohy, happened to be Mr. Lewis’s childhood friend.) The 2009 film adaptation won Sandra Bullock an Oscar for her role as Leigh Anne Tuohy and became Netflix’s most-rented DVD ever.

Now Mr. Oher has accused the family of stealing money he claims he was owed for the film rights — a situation that has prompted some readers to reconsider Mr. Lewis’s narrative, which they say favors the family’s perspective over Mr. Oher’s.

“Going Infinite” is controversial, too. Mr. Lewis normally avoids writing books about figures who are already world-famous. In this case, the character he thought was likable and relatively fringe — Mr. Lewis had barely heard of Mr. Bankman-Fried before their hike — has become a world-renowned pariah, a stand-in for an entire industry’s technical and moral failings.

So: What happens when a writer who is used to rapturous reception, with a knack for shaping stories, collides with an active public drama he doesn’t control?

Withholding Judgment, or Not?

Mr. Lewis, 62, has often been described as lucky. Since his 1989 breakout with the Wall Street memoir “Liar’s Poker” at age 29, he has become the dean of literary nonfiction best-sellers, cranking out titles that turn into coinages (like “Moneyball: The Art of Winning an Unfair Game” in 2003, about Billy Beane’s unorthodox embrace of statistics as general manager of the Oakland Athletics, which spawned a movie starring Brad Pitt) and cultural touchstones (like “The Big Short: Inside the Doomsday Machine” in 2010, about short-sellers who anticipated the subprime mortgage crisis, which spawned a movie starring Brad Pitt).

He did all this without breaking a visible sweat, somehow always in the right place at the right time.

“Going Infinite” seemed like another such marvel. Last November, after months of shadowing Mr. Bankman-Fried and interviewing his parents, friends and colleagues, Mr. Lewis had a character study and a collection of fun anecdotes. But it wasn’t a story.

That was OK, because there was initially no pressure to deliver the manuscript by a certain date. In 2010, after the success of “The Big Short,” Mr. Lewis stopped taking advances on his books. He splits the eventual profits down the middle with his publisher.

“I always leave myself with walkaway-ability,” he said. (After “Moneyball,” he sank three years into a project about minor-league baseball players before abandoning it.)

Feeling stuck, he solicited the advice of a film director friend who often helps him brainstorm. “He goes: ‘Man this is fantastic. But it’s not a movie, because there’s no ending. There’s no Act 3,’” Mr. Lewis said. “Two days later, it all collapsed.”

As FTX crumbled in the wake of reports that it couldn’t account for billions of its customers’ dollars, Mr. Bankman-Fried was taken into custody, then placed under house arrest. Still, the fallen crypto king continued to let Mr. Lewis interview him and even sit in on conferences with his closest advisers.

In the book, Mr. Lewis is careful not to weigh in on whether Mr. Bankman-Fried committed the crimes he’s charged with. “I leave it to the reader,” he said. “The radical thing here is to withhold judgment.”

He does have an opinion — “If I were in the juror pool, I wouldn’t just be silent,” he said — but is keeping mum for now.

His press tour, in which he seemed at times to abandon that neutral-observer stance, has provoked accusations of bias in favor of Mr. Bankman-Fried. When “60 Minutes” released a segment about the book last Sunday in which Mr. Lewis said FTX was a “great, real business” and referred dismissively to those who had lost money in the crash as “crypto speculators in the Bahamas,” the crypto and journalism slices of the internet melted down.

“Michael Lewis has lost the plot,” the influential crypto investigator Coffeezilla wrote.

A ProPublica editor, Jesse Eisinger, who won a Pulitzer Prize for his reporting on Wall Street’s pre-financial-crisis practices, joked: “Tired: Michael Lewis got lucky & was saved from a hagiography by SBF’s rampant & obvious fraud. Wired: Write the hagiography anyway!”

Mr. Lewis said he had expected blowback. “Some people will be threatened by the truth,” he said. “The full story will do violence to their mental picture. It’s been marvelous to me to watch people who know a fraction of what I know, who are willing to be much more certain than I am about what happened. I’ve earned my doubt. You haven’t yet earned your certainty.”

Mr. Lewis’s portrait of Mr. Bankman-Fried has also raised questions about the author’s relationship with his subjects. The risk of his immersive process is that Mr. Lewis ends up overidentifying with the people he calls “my characters.” (And they with him: After Mr. Lewis wrote about Senator John McCain, he told Mr. Lewis that he thought of him as his son.)

Mr. Lewis says he can write books only about people he likes. “If you said I had to go write about Harvey Weinstein, I’d say no. Why would I want to write about that?”

“I don’t think: hero, villain,” he said. “I think: great character, interesting situation, lots to teach the reader.”

At least some readers seem to appreciate that approach, and find the written work more measured than Mr. Lewis’s TV appearances. Bloomberg’s Matt Levine, who asked Mr. Bankman-Fried pre-collapse about his being in the “Ponzi business,” wrote a post midway through his reading of the book. He said reviews complained “that Lewis does not sufficiently explain that Bankman-Fried is Guilty and Bad, Actually,” but that wasn’t the book Mr. Levine wanted to read.

“If you want to read a moral condemnation of crypto theft, you can get that anywhere,” he wrote. “You go to Michael Lewis for character and story.” The book, in all its access-driven details, is “quite damning,” he added.

Other journalists have questioned whether Mr. Lewis’s relationship with Mr. Bankman-Fried was too friendly. In a new book about the crypto bubble, Zeke Faux, a Bloomberg investigative reporter, recounts watching Mr. Lewis “fawning” over Mr. Bankman-Fried during an onstage interview at the Crypto Bahamas conference in 2022. (Reviewers, including at this paper, have compared the two books, giving the advantage to Mr. Faux.)

When I mentioned this anecdote over lunch, Mr. Lewis leaned forward. “Here you have a person who’s written a book, and he’s trying to torpedo a rival book before it comes out?” he said. “That’s shocking. Talk about corrupt! So who do I think is more skeevy, Sam or him? I’d have to think about that.” (“He’s a friend of yours, right?” Mr. Lewis added. Indeed, Mr. Faux and I have known each other since summer camp.)

Mr. Lewis said he gives talks and hosts panels dozens of times a year. His fee is normally $150,000, he said, but he was not paid for the Crypto Bahamas panel. “I wasn’t different toward Sam than I would be towards anybody else,” he said. “It was a pleasant social interaction.”

The criticism is a good example of 20/20 hindsight, Mr. Lewis said. “At the time, I seriously doubt he would have seen it exactly the way he wrote it,” he said of Mr. Faux. “Or if Sam Bankman-Fried was still worth $100 billion and FTX was still a huge success,” he said, “nobody would think twice about that interaction.”

“I stand by what I wrote,” Mr. Faux wrote in an email.

‘A Walking Social Satire’

Mr. Lewis speaks with the wide vowels of a born New Orleanian and, no matter the topic, the enthusiasm of a boy who has just seen a giant. When I first walked into his office in Berkeley — a small cabin in the four-building compound where he lives — he immediately launched into a story, barely looking up from his phone, as if we were old friends. (It involved his son, the Golden State Warriors and some courts they were going to visit that evening.)

Then he was off on a series of jags about his high school baseball coach (the subject of his 2005 book, “Coach: Lessons on the Game of Life”), the first piece of fan mail he ever received and why he stopped subscribing to Library of America editions. (They ran out of great writers, apparently.) Without interruption, it seemed, he’d find a way to keep stringing the stories along forever.

Which is a lot like how his books have worked: The success of “Liar’s Poker” gave him access to the traders who talked to him for “The Big Short,” one of whom introduced him to the protagonist of “Flash Boys.”

Then in the fall of 2021, Brad Katsuyama, one of the “Flash Boys” upstarts who sought to neutralize the advantages of high-frequency traders, asked him to “look into” Mr. Bankman-Fried, Mr. Lewis said. Mr. Katsuyama, now a friend, was considering a deal with FTX but couldn’t get a read on its oddball leader. (Mr. Katsuyama declined to comment.)

Mr. Lewis liked Mr. Bankman-Fried instantly. Though they are superficially opposites — the wild-haired man-child in an oversize T-shirt alongside the WASP who favors seersucker — they share a resistance to dogma, Mr. Lewis said. The quant child of Stanford law professors who grew up discussing utilitarianism at the dinner table and blogged during college about the San Francisco Giants, Mr. Bankman-Fried is, in a way, a Michael Lewis character grown in a lab.

Mr. Lewis was also drawn to the younger man’s willingness to dream big, from donating a billion dollars in the 2024 presidential campaign to someday retiring the debt of the Bahamas. And by the self-justifying tenets of effective altruism, the more money Mr. Bankman-Fried made, the more good he could do.

“It felt like Ferris Bueller with twenty-two-and-a-half billion dollars,” Mr. Lewis said.

He was especially fascinated by the contrast between the seriousness of Mr. Bankman-Fried’s stated purpose — saving humanity from extinction — and the dubious industry he was riding to get there.

The way the world courted Mr. Bankman-Fried at his peak only heightened the absurdity. In one of the book’s early scenes, he plays a computer game while on a video call with Anna Wintour, who all but asks him to sponsor the Met Gala. “This is like a walking social satire,” Mr. Lewis said.

Soon the author was commuting to the Bahamas regularly to spend time with Mr. Bankman-Fried and his colleagues Caroline Ellison, Nishad Singh and Gary Wang — who have all pleaded guilty and are likely to be called to testify against their former boss.

After a few visits, Mr. Lewis could rifle through Mr. Bankman-Fried’s desk without anyone blinking. He’d hang out in an FTX conference room, and employees would rotate through for interviews.

According to Mr. Lewis, there were periods when he saw more of Mr. Bankman-Fried than Mr. Bankman-Fried’s parents did: “They had to go through his scheduler to get 15 minutes with him. And he would often not show up.”

Joseph Bankman and Barbara Fried, who received millions from their son (they dispute that any of it came from customer funds) and, in Mr. Bankman’s case, did advisory work for FTX, would ask Mr. Lewis to relay things that their son had told him, Mr. Lewis said.

Mr. Bankman-Fried would even solicit Mr. Lewis’s advice on key decisions, including whether to invest in Elon Musk’s Twitter purchase. (Mr. Lewis said no.) “They’d be like, ‘Did you tell him not to do it?’” (Mr. Bankman and Ms. Fried did not respond to an interview request.)

After FTX collapsed, some sources, like Ms. Ellison and Mr. Singh, dropped off Mr. Lewis’s radar as they got legal counsel. Others became more essential, including Constance Wang, FTX’s former chief operating officer, who showed Mr. Lewis a trove of documents detailing the company’s expenditures and listing its creditors. (Lawyers for Ms. Ellison and Mr. Singh declined to comment. Ms. Wang did not reply to a request for comment.)

Mr. Bankman-Fried was under house arrest at his parents’ home in Palo Alto, Calif., an hour’s drive from Mr. Lewis. “He couldn’t do anything but spend time with me,” Mr. Lewis said. “And he was happy for the company.”

Mr. Bankman-Fried’s parents were nervous about his presence from the start, Mr. Lewis said. But at some point, even after FTX fell apart, they figured the damage had been done. During a conclave of advisers at family headquarters, one participant eyed Mr. Lewis suspiciously, he said, and “Joe said: ‘It’s too late. If he’s going to kill us, it’s already happened.’”

On Nov. 11, the day FTX filed for bankruptcy, Matthew Snyder, Mr. Lewis’s agent at Creative Artists Agency, blasted out an email announcing that the movie rights to Mr. Lewis’s book were available, and the message leaked to the Hollywood press. Mr. Snyder wrote that the events of the previous week “highlighted the rivalry” between Mr. Bankman-Fried and Changpeng Zhao — the head of the Binance crypto exchange, who had helped draw attention to FTX’s problems — and that “Michael likens them to the Luke Skywalker and Darth Vader of crypto.”

Mr. Lewis denied that this was his initial framing for the book. “He was just pitching the movie,” he said. “That’s what they do.”

It worked. Apple bought the rights for $5 million.

Mr. Lewis didn’t sit down to write until January, and the book needed to be finished by mid-August to publish at the start of the trial. Eight months is a tight time frame, but Mr. Lewis said he usually wrote his books in six. He wrote “Moneyball” in four.

Revisiting ‘The Blind Side’

Many of Mr. Lewis’s books have elicited a similar line of critique: He spins a great yarn, but the world is more complicated than he presents it. Did sabermetrics, the analysis of baseball statistics, push the Oakland A’s to victory, as “Moneyball” suggested, or did they just have a strong roster of traditionally scouted players? Were the Wall Street rebels of “Flash Boys” moral paragons when they outsmarted the “rigged” system of high-frequency trading, or just clever guys with an idea for a business?

And in “The Blind Side,” were the Tuohys as heroic as portrayed? This question re-emerged in August when Mr. Oher asked a Tennessee court to dissolve the conservatorship he had been under with the Tuohys, giving them control of his financial affairs. (It was formally dissolved last week.) He also sought money he said he should have earned from the movie. The accusations drove a new round of opinion pieces about the exploitative nature of college football and the persistence of white savior narratives.

When we spoke, Mr. Lewis rejected the notion that the Tuohys had withheld money from Mr. Oher, who is now 37. “I thought that was incredibly defamatory,” he said. “This kid is making up nasty lies about people who did quite a bit for him.” (A spokesman for the Tuohys and a spokeswoman for Mr. Oher declined to comment.)

Mr. Lewis said the only reason the Tuohy family — including Mr. Oher — had received any money for the movie was that he had voluntarily shared half his own stake, “out of the goodness of my heart.” The Tuohys then split their share evenly within the family, with about $70,000 going to Mr. Oher, Mr. Lewis said.

At some point, according to Mr. Lewis, Mr. Oher turned on the Tuohys, who said he was in their will at the time, and therefore entitled to a third of an estate they claimed was worth $300 million. “He threatened them saying he’s going to destroy their reputation unless they write a check for $15 million,” Mr. Lewis said.

“I don’t know what happened to him that has caused him to feel the way he feels,” Mr. Lewis said. To The Guardian, he speculated, “This is what happens to football players who get hit in the head: They run into problems with violence and aggression.”

Mr. Lewis called the outcome “heartbreaking,” but said it didn’t change his view of the original story. “I don’t think there’s a word in that book I would change,” he said.

A Painful Loss

In 2021, Mr. Lewis’s 19-year-old daughter, Dixie Lee Lewis, was riding with her boyfriend, Ross Schultz, near Lake Tahoe when their car veered into an oncoming truck. Both were killed.

After the accident, Mr. Lewis worried he’d never write again. He also felt out of step with what he was told the grieving process was supposed to be. People who had lost children would write to him offering advice, or saying they knew what he was going through. These letters often left him cold.

“One of the great themes was you need to learn how to live with the guilt,” he said, but he didn’t feel any guilt.

Therapy and religion didn’t appeal, either. “I’ve always thought friends were better to talk to than some stranger,” he said.

It has brought him closer to his closest circle, which includes Jacob Weisberg, a co-founder of the podcasting company Pushkin Industries, for which Mr. Lewis hosts a show. “Michael was kind of once a byword among his friends for having a charmed life,” said Mr. Weisberg. “Nobody can say that anymore.”

This discrepancy between the way he’s supposed to feel and the way he actually feels is often an opening, Mr. Lewis said: “That disconnect is the beginning of having something to write about.” He hasn’t ruled out writing a book about losing Dixie, or maybe doing a one-man show.

I asked Mr. Lewis if his loss affected the new book. He said no, but added that I wasn’t the first to suggest it had. He said his copy editor for “Going Infinite” had told him that after losing Dixie he was writing characters in a more empathetic way. Indeed, parts of the book — particularly about Mr. Bankman-Fried’s depression and alienation — have more emotional weight than anything he had written before.

“So I can’t dismiss the possibility that Dixie is in there somewhere,” Mr. Lewis said.

The Fights Are Finding Him

At a recent panel to promote a new documentary about Tom Wolfe, Mr. Lewis contrasted himself with Mr. Wolfe, who famously feuded with Norman Mailer and John Irving: “In a genteel way, he was looking for a fight in a way I wouldn’t. I don’t like getting into fights with writers.”

Yet lately the fights seem to be finding him. In a September profile of the biographer Walter Isaacson in New York magazine, the journalist Shawn McCreesh quoted Mr. Lewis telling a story about a young Mr. Isaacson’s being trotted out during three separate assemblies at the private New Orleans school they both attended — Mr. Isaacson nearly a decade earlier — and presented as the model alumnus. As quoted in the piece, Mr. Isaacson seemed to delicately suggest that Mr. Lewis’s account was embellished — or, in his words, “more beautiful” — which led Mr. McCreesh to connect the story with the Oher controversy and concerns about Mr. Lewis’s narratives being “too … beautiful.”

Mr. Lewis said a classmate had since verified his version of events. For the first time during our conversations, he seemed on edge. He said he planned to clear the record while onstage with Mr. Isaacson in New Orleans during his book tour.

“I’m going to open by saying I want to talk about this New York magazine guy — this prick who did this — and what actually happened,” Mr. Lewis said.

He bristled at insinuations of embellishment. “What it tells me is the person who’s writing this has a very different process than I do,” he said. “They think that for them to get this level of material, they would have had to make it up.” (Mr. McCreesh declined to comment.)

He has faced criticism from fellow journalists before. In 1997, Marjorie Williams wrote a withering story about Mr. Lewis for Vanity Fair. In it, she interviewed ex-girlfriends, cast doubt on his “truth-telling naïf” persona, and questioned his journalistic ethics by pointing to factual discrepancies between his books and the magazine articles from which they were adapted.

“I thought it was kind of dumb,” Mr. Lewis said of Ms. Williams’s profile. “But I couldn’t do much about it, except go spend Vanity Fair’s money when I became a writer there.” When Graydon Carter hired Mr. Lewis to write for the magazine a decade later, he paid Mr. Lewis $10 a word. (Ms. Williams died in 2005.)

Mr. Lewis said his inability to back down from a fight was one reason he avoided posting on X, formerly known as Twitter. “As a Southern male, it’s painful to turn the other cheek.”

During our last meeting, in a sumptuous bar at the Greenwich Hotel, where he likes to stay when he visits New York, I asked Mr. Lewis if he ever thought about slowing down. “Like not writing as much?” he replied. “Like losing your fastball,” I said.

He chuckled. “I have not felt anything but this feeling of increasing powers,” he said. “I trust my stuff more than I’ve ever trusted it.”