BEVERLY HILLS, Calif. — Conan O’Brien fell under the spell of the historian and biographer Robert A. Caro when he was a student at Harvard in the 1980s. The book that made him a fan was “The Path to Power,” the first installment of the multivolume epic “The Years of Lyndon Johnson.”
Mr. O’Brien devoured the second, third and fourth volumes of the still-growing series, and across his 26 years as a talk-show host, he put in numerous requests to interview the Pulitzer Prize winner. Mr. Caro found time over the years to appear on shows hosted by Jon Stewart and Stephen Colbert, but he always said no to Mr. O’Brien.
On Tuesday, there was a happy resolution.
“I’m anxious,” Mr. O’Brien said as he rode in a black S.U.V. from the Warner Bros. Studio in Burbank, where he tapes his TBS show, to Temple Emanuel in Beverly Hills, where he would interview Mr. Caro. “It’s very unusual to meet somebody whose work you’re so familiar with.”
In an interview with The New York Times last year, Mr. O’Brien said, “The Lyndon Johnson books by Caro, it’s our Harry Potter,” and described in detail his many thwarted attempts to sit down with Mr. Caro. The author finally caved on the occasion of his tour for “Working,” his new, relatively slim book on his writing and research methods.
At 83, Mr. Caro is enjoying a moment of appreciation, and he has made appearances in recent days in Austin, Tex., Philadelphia and New York, his home city. Mr. O’Brien, 55, acknowledged that he had not exactly landed an exclusive.
“People keep saying, ‘I heard him on this podcast,’” he said. “‘He dropped in at Coachella.’ ‘He opened a mall in Paramus.’”
The S.U.V. turned onto North La Cienega Boulevard. Mr. O’Brien pointed at a building.
“That’s where I got started in this business,” he said. “The Coronet Theatre. I took improv classes there with a talented young person named Lisa Kudrow. If you had told me then that 33 years from now I’d be in a car with a writer from The New York Times on my way to interview Robert Caro, I would have said, ‘That sounds about right.’”
In the rabbi’s study at Temple Emanuel, he didn’t have to wait long for Mr. Caro.
“They probably told you,” Mr. O’Brien said. “I’m a fan to a disturbing level.”
“I want to say, if I’ve ever been asked to be on your show, my publisher never told me,” Mr. Caro replied.
“I like this way better,” Mr. O’Brien said. “I respect you too much to have you on my show.”
After a handshake that lasted 30 seconds, they sat at a conference table. Then something strange occurred. Mr. Caro effectively started interviewing Mr. O’Brien. What was his thesis at Harvard? After Mr. O’Brien said it was on the works of Flannery O’Connor and William Faulkner, Mr. Caro asked him if he had ever spent time in the South and followed up by asking the host what he thought of the region’s relationship to the larger United States.
“Wow, I love that you’re asking my opinion on anything,” Mr. O’Brien said.
The conversation tilted toward President Trump.
“You don’t know if this is an aberration or not, if Trump is something outside, and he’s going to lose, and we’ll forget,” Mr. Caro said. “Or, is he the first of the mad Roman emperors?”
They briefly went over Mr. Caro’s appearance on Mr. O’Brien’s new podcast, “Conan O’Brien Needs a Friend,” which was scheduled for the next day. “We have a very young audience,” Mr. O’Brien said. “I want them to hear about work ethic.”
It was almost 7:30. Show time.
They stepped out of the study and into a standing ovation from the 550 people who had paid $ 20 for general admission or $ 38 for a seat and a copy of “Working.” Mr. O’Brien called the event, which had been organized by Writers Bloc, a nonprofit literary series in Los Angeles, the “thrill of a lifetime.” He added, “I also want to thank you, Mr. Caro, for finally writing a book that’ll fit on my night table.”
Mr. O’Brien gave a shout-out to Mr. Caro’s wife and longtime working partner, the historian Ina Caro, who was seated in the front row. He noted the dedication she displayed in agreeing to move with her husband to the Texas Hill Country, where President Johnson was raised, back when Mr. Caro was looking for insights into his subject’s early years.
Mr. O’Brien added that his wife, Liza Powel O’Brien, who was also in attendance, wouldn’t have gone along with such a thing; but Ms. Caro, he said, was completely on board.
“Not exactly,” Ms. Caro whispered to the person seated next to her.
Mr. O’Brien and Mr. Caro dug into Lyndon Johnson’s life. His father. His mistress. His ambition. They also talked at length about Mr. Caro’s writing process. As the discussion went on, Mr. O’Brien found himself far from the talk show format. Mr. Caro spoke the way he writes, answering questions in shapely monologues that lasted five or six minutes.
An hour in, Mr. O’Brien asked the author how he felt about the Horace Mann School, his high school alma mater in the Bronx, having named a prize after him.
“No one has ever asked me that,” Mr. Caro said.
“I’ve been waiting a long time,” Mr. O’Brien replied.
The host then asked Mr. Caro if he agreed with Ernest Hemingway’s comment that a writer should not “exhaust the fuel tank in one writing session,” so that it’s easier to start again the next day.
“Yes, and you’re the first person that ever mentioned that,” Mr. Caro said, before noting that he had written his thesis at Princeton on Mr. Hemingway.
“Why am I in comedy?” Mr. O’Brien said.
Did Mr. Caro ever take breaks? Sneak away from his desk to an afternoon movie?
“See the new ‘Avengers,’” Mr. O’Brien suggested. “Ina doesn’t have to know about it.”
“Never in my entire life,” Mr. Caro replied.
Mr. O’Brien proposed coming by Mr. Caro’s office one day and taking him to a matinee.
“If I don’t answer,” Mr. Caro said, “it’s because I’m so deep in the work.”
After a Q. and A. session and another round of applause, Mr. Caro seemed pleased. “I thought these questions tonight were exceptional,” he said in a side room. “Incisive.”
To think, the event had almost been scuttled.
On Tuesday morning, Mr. Caro’s flight from Austin to Los Angeles was canceled. Mr. Caro said he immediately thought of Mr. O’Brien. “That was in my mind,” he said. “I said, ‘He’s never going to believe it, if I said the flight got canceled.’”
His publishing house, Knopf, had to make a decision: pull out of the interview, or find a way to make it happen. The publisher quickly booked a charter flight — Mr. Caro described it as an eight-seater jet — to Van Nuys Airport.
“The downside of canceling the event was disappointing Mr. Caro’s legion of admirers,” said Paul Bogaards, a spokesman at Knopf. “Additionally, the prospect of sending Conan into an irrevocable tailspin did not sit well with me. God knows, he’s waited long enough for this to happen.”