Jim Carrey is not doing well at all.

At the start of the novel “Memoirs and Misinformation,” we find Carrey, its protagonist, in the midst of an existential crisis, crushed by self-doubt and confined to his Los Angeles home, where he subsists on a diet of Netflix, YouTube and TMZ. His successes as an actor, in projects both comedic and dramatic, are distant objects in the rearview mirror, and now he is fixated on his own inevitable demise and the eventual end of the universe.

So begins a satirical adventure in which Carrey plumbs the chasms of Hollywood’s self-obsessed culture. While he searches for meaning in his life and career, this Carrey is also trying to choose among starring roles in a Mao Zedong biopic and studio movies based on children’s toys; contending with catastrophic wildfires, an all-female cadre of eco-terrorists and a U.F.O. invasion; and rubbing elbows with the likes of Nicolas Cage, Gwyneth Paltrow and Anthony Hopkins.

The Jim Carrey of “Memoirs and Misinformation” also happens to share a name and several key biographical details with Jim Carrey, the ever-changing star of films like “The Mask,” “The Truman Show,” “Eternal Sunshine of the Spotless Mind” and “Sonic the Hedgehog,” who wrote the book with the novelist Dana Vachon (“Mergers and Acquisitions”).

“Memoirs and Misinformation,” which Knopf will release on July 7, is the result of a yearslong collaboration between these two unlikely partners. It is a fictional narrative that relies on facts from the life of its celebrity co-author — and on his access to a world of maximum privilege and alienation — to tell a story that its creators believe is especially timely.

As Carrey explained in an interview earlier this month, “It’s the end of the world, and we have the perfect book for it.”

“Not the end of civilization,” he continued. “Just the end of a world, the selfish world. We’re getting over the Ayn Rand, ‘you can be a jerk and we can all live in a paradise of jerks’ thing. That’s what we’re going through.”

For Vachon, working on the novel gave him a new perspective on the nature of stardom, as well as a greater appreciation for Carrey in all his complexities.

“It was a journey into forbidden realms of stardom and the wages of great artistry,” Vachon said. “He’s like an abalone diver — if he doesn’t go down to those depths, he doesn’t come back with anything. You can’t create great art, just living blissed out on the surface.”

Speaking together over Zoom, Carrey and Vachon talked about the making of “Memoirs and Misinformation,” the joys of playing on the boundary between fact and fiction, and how they expect Tom Cruise will react to it. These are edited excerpts from that conversation.

How did the two of you first get connected?

JIM CARREY We met about nine, 10 years ago, when Twitter first became a big thing and people were still experimenting with it.

DANA VACHON It had been a really depressing winter. I was in Williamsburg, everything was closing and all the construction was arrested. And one morning I looked at Twitter and Jim had tweeted “BOING.”

CARREY I was just trying to create another version of the Force or chi. The energy that does everything positive in the world.

VACHON So in our first communication, I replied, “BOING that [expletive].” I’m something of a Hitchensian skeptic and he’s very mystical. But I looked at it and I thought, it would be great to make something really true with an artist of that caliber. But that’ll never happen. And a year later, we were working on it.

A Twitter exchange was all it took?

VACHON We had a manager in common who said, “Maybe you guys should talk,” and nothing came quite of that. After our first meeting, I was like, “He’s a lovely person — I’ll definitely never talk to him again.” But we kept talking.

CARREY This guy’s got an integrity that just doesn’t exist anymore. Immediately, we were friends, and the friendship got deeper as time went on.

Did you ever consider writing a factual memoir of Jim’s life?

CARREY There’s nothing, at this point in my artistic life, more boring than the idea of writing down the actual events of my life in some chronological order. Trying to expand my brand. This is not that. It’s a labor of love that we couldn’t stop. It started out as a little volley back and forth, here and there, and in the last few years it was eight hours, 12 hours most days, just grinding together in a room. But even when we butted heads, we always came up with something more interesting than we had initially conceived.

The protagonist of this novel is named Jim Carrey and he has lived a life very similar to yours. But who is he?

CARREY Jim Carrey in this book is really a representative — he’s an avatar of anybody in my position. Of the artist, of the celebrity, of the star. That world and all its excesses and gluttony and self-focus and vanity. Some of it is very actual. You just won’t know which is which. But even the fictional qualities of the book reveal a truth.

Dana, what was it like for you to get to know the real Jim, as opposed to the version of himself that he presents onscreen?

VACHON One of the first times he contacted me, he was watching the John Barrymore “Jekyll and Hyde,” which came to inform the story. He was telling me, “Watch Barrymore. Watch the economy of his face in this.” And I was like, oh, wow, Jim Carrey watches a lot of Netflix.

CARREY There were times when I was so afraid. I see a dead John Lennon on a gurney on YouTube. And I’m completely out of my mind because I realize that there will be selfies taken when my body falls. Somebody’s going to be looking at it as a novelty. That terror and mortal fear of wanting to make a good corpse drove me to the bathroom to make myself up before bed so that if I did die in the middle of the night, I would be presentable to an adoring public.

Together you’ve devised some strangely affecting scenes, like when the fictional Jim finds himself working alongside a digitally rendered rhinoceros containing the essence of Rodney Dangerfield.

VACHON Writing that was really intense. Jim’s like, “I don’t know what you thought we were doing, but we’re writing some Rodney Dangerfield bits for the next two or three days.” At the end of it, I’m pretty tired and Jim comes out with this turtle box and he opens the box.

CARREY [His widow] Joan Dangerfield, after Rodney passed, gave me this beautiful leather-bound box with Rodney’s favorite shirt and his pot pipe. If you knew Rodney, you’d know that’s pretty much the Holy Grail for Rodney. [Dangerfield voice] “It keeps me creative, man.”

Was there any point in your process that Jim said you’re taking things too far or we can’t go there?

VACHON He’s the only person in his position who would be like, “I’m OK having a climactic combat scene where I just load ammo. I don’t need any confirmed kills. In fact, I don’t even need a gun.”

CARREY I was talking to Nic Cage a couple days ago. I hadn’t told him anything about the book and then one day I sprung it on him, and he just said, [Nicolas Cage voice] “Jim, I’m so honored, man. You have no idea.” I said, I gave you all the best lines. [Cage voice] “It’s unheard of!” He’s so excited about it.

Have you told the other celebrities you reference by name that they’re characters in the book?

CARREY We’re sending everybody books with letters of explanation of what we’re doing.

VACHON “Dear Gwyneth.”

CARREY It’s satire and parody but also done with reverence. Most of the people in this book are people whom I admire greatly.

Does that include the character you say for legal purposes will be referred to only as “Laser Jack Lightning”?

CARREY That’s just us poking fun at the litigiousness of Hollywood. I know Tom Cruise. He may sock me, but hey, I’ll take the beating for a piece of art. I think he’s going to love it.

Dana, were there ever times when this project felt like a real-life version of “Sunset Boulevard”?

VACHON Totally.

CARREY [eyes widening in delight] Who does that make me?

VACHON “Barton Fink” was more what would come to mind. But by the point I had concerns, it was too late.

CARREY This took a grip of us.

VACHON And also, it wasn’t eight years of total work. We really worked hard, intensely, for the last two. But we were always both working on other things.

The book very vividly depicts its protagonist’s intense frustration with Hollywood and his estrangement from his own work and accomplishments. Jim, how much does that represent your own true feelings?

CARREY “The Truman Show” was not a mistake. I’m a guy that suddenly looked up one day and started seeing all the machinery and the lights falling from the sky. Every project is a little bit of me recreating myself, tearing the old self down and exploring something new. My whole career I’ve asked a lot of my audience, and they’ve allowed me to do these things. I think they expect that of me, in a certain way. They don’t expect convention.

Dana, do you think you’ve emerged from this project a different writer?

CARREY [to Vachon] Watch it. Watch it.

VACHON I don’t think you can spend eight years working with somebody and not be changed. It freed me. People in New York spend many years on a single story. In L.A., there’s a deftness and a confidence in, let’s just get this done, versus the East Coast idea of, we’ll listen to God. Writing’s lonely, so it was great to have a writing partner. It could be 3 o’clock in the afternoon, you’d be like, “Yo, dude, what’s going on? What did you do today?” And it still felt like work.

Jim, do you think you’ve arrived at a different understanding about creativity or celebrity?

CARREY An artist is a custodian of a divine spark and these people, no matter how complex or strange their character, they have a connection to something divine and they can give you that connection through their work. That’s all I’ve ever wanted. Whether I was doing something funny or serious, all I’ve ever wanted, from the time I was a little child, was to free people from concern. This book, I think, is just an example of that. And I think we get there in the book. We get to a place where we give them a touch of that.

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