Mr. van Hove has followed Ms. Yanagihara’s lead, keeping the novel’s cruelty center stage rather than ushering it into the wings, where it might be easier for audiences to tolerate.

“I’m never concerned about it being too brutal,” he said during a rehearsal break. “I’m not afraid of darkness, I’m not afraid of violence, I’m not afraid of extremities. Theater is there to represent the actual reality outside. I think that’s the function of art and theater — you look at things that you abhor, that you really are nauseated by, but that’s important because it’s a cleansing process.”

Mr. van Hove said he first encountered “A Little Life” after two friends independently gave him copies of the book, saying the same thing: “This seems like something for you.” After inquiring about the rights, he received a third copy with a personal note from Ms. Yanagihara, saying that she’d be “honored” if he’d bring it to the stage.

Ms. Yanagihara, who is the editor of T: The New York Times Style Magazine, said in a telephone interview that she saw Mr. van Hove’s production of “The Crucible” on Broadway in 2016. “I just thought he was a genius, someone who did some very interesting, irreverent and disruptive things on stage,” she said.

The two went back and forth on the concept for the script, and had some “spirited disagreements,” Ms. Yanagihara said. But she said that she had ultimately left it mostly in Mr. van Hove’s hands. “It was a leap of faith,” Ms. Yanagihara said.