Two comedians walk into a theater and candidly speak about their struggles with addiction and fatherhood.

There’s no punchline to that premise, though there are jokes served between “My Next Guest Needs No Introduction” host David Letterman and John Mulaney, his guest for the special episode now streaming on Netflix. And it’s a joy to witness the mutual admiration and sincerity during conversations at a theater in Mulaney’s hometown of Chicago, his Saint Ignatius College Prep high school and a restaurant with a very special guest, Mulaney’s dad, Chip, whom fans have met through the comic’s standup.

(Starting Friday, Mulaney hosts a live show, "John Mulaney Presents: Everybody’s In LA," featuring famous faces in town for the Netflix is a Joke Festival. Additional episodes of the series will be released May 6-10.)

How to watchJohn Mulaney's upcoming live Netflix series 'Everybody’s In LA'

John Mulaney wanted to leave rehab but stayed for this reason

Mulaney, 41, celebrated three years of sobriety last December, but told Letterman he “had zero gratitude” for his star-studded intervention and rehabilitation at the time.

“You try to hide a drug habit for years successfully, getting found out is quite embarrassing,” he says. “And then you’re totally powerless at an intervention like that.”

Mulaney says he decided to leave the treatment center after just four days, but was persuaded by a doctor to stay. “’John, we both know how this movie ends,’” he recalls the physician telling him, “and that was it. I just kind of nodded and went back to my room and stayed.”

Though Mulaney now says he’s an alcoholic and drug addict, he previously wouldn’t have recognized his addiction to prescription pills. “It’s just how I lived every day,” he says. “You wake up, take a couple Adderall, feel there’s too much of an edge, take half a Klonopin, got a little too sleepy, have to finish a script, and then got on the phone, take another Adderall. The Adderall is wearing off, which isn’t the best feeling, so let’s just take one Adderall with half a Xanax and just ride that all day long.

“It was exhausting,” Mulaney says, “and it was a fulltime job.”

Letterman, 77, reflects on his own battles with alcoholism. He says he began drinking at 11 and stopped at 34, shortly after landing his NBC talk show “Late Night,” which debuted in 1982. “I thought I’ll never forgive myself if the alcohol causes me to lose that show,” he says.

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John Mulaney’s son Malcolm is ‘that thing I couldn’t find’

Mulaney tells Letterman that he really felt complete after he and partner Olivia Munn welcomed son Malcolm in November 2021.

“I was starstruck when I met him,” the former “Saturday Night Live” writer says. “I went, ‘Oh there you are. You’re that thing I couldn’t find.’ I was looking in not good places...”

Mulaney describes Munn’s pregnancy as “a big surprise” to both. “We were really (like) ‘Huh,’” he says, getting laughs from the crowd. He says the sense of safety he felt from knowing how much his parents cared about each other is something he and Munn try to replicate. “So Olivia and I try to show Malcolm how much we love each other.”

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John apologizes to his dad, Chip Mulaney: ‘I’m sorry you were so scared’

Fans of Mulaney’s standup will undoubtedly be delighted to meet Mulaney’s father, Charles “Chip” Mulaney.

“My dad is a lawyer, and he was a debate-team champion so he would pick us apart psychologically,” Mulaney explains in his 2018 stand-up special, “Kid Gorgeous at Radio City” (now streaming on Netflix).

During his routine, Mulaney also remembers when Chip interrupted his wife’s story about a ghost in Mulaney’s childhood home. “And then my dad said, ‘Let’s change the subject!’” Mulaney told the audience. “And I think he was just doing that dad thing of like, ‘This is a weird topic, and I want to talk about a book I read about World War II.’ But the way it came off was that he definitely killed that little girl!”

“Ah, none of us really know our fathers,” Mulaney added.

But Mulaney reveals to Letterman that he idolized Chip growing up, and the three share a tender moment at a restaurant. Chip says he was surprised by his son’s dependency on drugs and admits to harboring a daily fear that he'd die from it. Mulaney then places his hand on dad’s arm and offers a simple yet moving apology: “I’m sorry you were so scared.”

“Well, it’s a normal, loving reaction,” Chip responds.

Letterman realizes the power of the moment. “Forgive me,” he says, “I find the three of us here touching. I just do.”