In our series “Undercover,” we have explored the complicated business of book blurbs and looked into how audiobooks are made. This week, we ask a question: what makes a good screen adaptation of a book we love?

It might seem like everything on tv or at the movie theaters these days is based on a book. And that’s not just your imagination! Last year, Vulture reported on 60 book adaptations in 2022 alone.

Which maybe isn’t surprising. From The Lord of the Rings to Harry Potter, from Jaws to The Godfather, some of the biggest blockbusters and franchises in movie history are adaptations of books.

So what makes a film or tv adaptation great? And how do all the people involved think about their duty to the book while making something totally different?

Let’s start from the beginning. Before a book is reborn as a movie, it has to be optioned. That’s when a production company or actor buys the rights to make the story. It’s basically a rental, and it can last a year or more.

The cost of an option depends on a lot of factors, so it can range anywhere from $500 to hundreds of thousands of dollars.

For the most part, though, it’s not a life-changing amount of money. “No one’s retiring off of their novel being optioned for television,” says author Cynthia D’Aprix Sweeney. Her hit novel The Nest was optioned shortly after it came out in 2016. We’re still waiting on the TV series.

“You need all the stars to align, and it just doesn’t happen that often,” she says. “What would actually help an author is if it sells more books.”

Selling more books is what the publisher is banking on, too. Usually, publishing houses don’t get any money when a book is optioned. The publishers usually re-release the book with a new cover — it may have an image from the movie, or a badge that says “Now on HBO,” in the hopes that new fans of the show or movie will translate to a new audience for the book.

These days, anything can be optioned: a book, a graphic novel, a podcast, even a viral twitter thread. Between network TV and all those streaming platforms, everyone is looking for content.

But the amount of things that are getting optioned is much, much higher than the amount of stuff that actually gets made.

Danya Kukafka, a book agent and author, says she tells her clients to keep their expectations low — just because a project is optioned doesn’t mean it’ll make it to the big screen. “Think of it as a cool thing that could happen, but probably won’t.”

One author we talked to estimated that only 5% of the books that are optioned actually become a TV show or movie. When I ran that estimate by Dan Smetanka, the editorial director for Catapult book group, he thought even that seemed high.

“Oh, that’s a generous number,” he says.

“It’s a tough journey. Think of all the people who have to be involved in getting a book to some sort of dramatic adaptation. It’s endless. That’s why so many things are optioned and then never get off the ground.”

If a project does get off the ground, there’s a lot to consider. After all, people who are book nerds generally agree on one thing about film or TV adaptations: The book is always better! But is that even a fair comparison?

Think about it. A book can cover hundreds of years. It can have a gazillion characters. It can explore the inner thoughts of all gazillion of those characters. It can span continents or even constellations.

Which means, for a filmmaker, there are lots of different criteria to consider, and a lot that inherently has to change.

Pretty much everyone we talked to said the most important thing is to convey the essence of the book without getting every plot point exactly right. In a lot of ways, it really comes down to vibes.

“At a certain point, you don’t remember the plot of every book, you remember what you felt like. That’s what you’re going for,” says Attica Locke. She has written for TV and is the author of several books. She is also a big reader herself. She says it’s much more about the feeling than the exact story.

TV critic Linda Holmes agrees. “In order to make a really good adaptation, you have to have a really sound understanding of what the point of the book is. You want to start from the same bones and build something that’s fundamentally different in a lot of ways.”

Tom Perrotta has also thought about this a lot. He’s the author of 10 books, and a lot of them have been adapted in some way. His book Election became a movie with Reese Witherspoon, and The Leftovers was a series on HBO.

He says as an author, it’s important to be able to let the new thing be its own new thing. “To some degree, there is just a big letting go for the writer of the original material. Sometimes that can be painful in the moment, but it’s almost always for the best.”

One idea is to think of the movie or TV version of a book as a cover song. It encompasses the fact that while these two things can share so much in common, they’re also fundamentally different.

Celeste Ng thinks of it that way, too. She’s the author of three books now, and her second book Little Fires Everywhere became a Hulu show with Reese Witherspoon and Kerry Washington in 2020.

She loves cover songs. “What I love about them is that you hear a song that you know. You hear a melody. You hear familiar words. But my favorites are the ones in which you really hear how the new artist has put their spin on it. If you get a cover song that’s too much like the original, in a way, I’m sort of disappointed.”

Some authors want to take on the role of executive producer and usher the show into the world themselves. Others want to write the screenplay version. But a lot of the time, they just let someone else take on the project. That’s what Celeste did with Little Fires Everywhere. She says she’s acutely aware that she’s an author, not a screenwriter.

“I wrote this as a book and I can really only see it clearly as a book myself,” she says. “I wanted to let the screenwriters take the ball and run with it. Because in a way that gave them the freedom to make this into something different.”

“I remember, she was going to come to our writers room to hang out,” says Attica Locke, who was a producer on Little Fires Everywhere. “And our showrunner was like, ‘Oh, she’s just gonna sit and observe.’ And I’m the only novelist in the room. And I was like, ‘That’s not gonna happen.’ And she had the best attitude.”

“I think being a novelist in that room taught me to hold both things: hold the book, and then hold this new thing that you’re making. To not feel like the book is going to be obliterated by the adaptation, and to also give the adaptation permission to be fresh and new.”

And the writers really did make something fresh and new with Little Fires Everywhere. In the book, the story revolves around two families: one is an affluent couple with general wealth and three high school aged kids.

The other is a single mom who is a wandering artist and her teenage daughter. To make ends meet, the artist mom ends up being a house cleaner for the other family and all of the kids become entangled.

As you may be able to guess, the book covers a lot of issues of class. When it came to the racial identities of the characters, Celeste was intentionally vague. But when the showrunners came to her with the idea that Kerry Washington would play Mia the housecleaner, Celeste was all in.

“I loved that idea,” she says. “I did not want to write Mia as a Black woman in the novel, because I didn’t want to assume that I could understand what a Black woman’s experience would be in the way I would need to do justice to that character. But I was like, ‘But Kerry Washington can.’”

Celeste says she was also glad that the writers’ room included many Black women. “They can try and flesh out that experience and portray it and look at these dynamics in ways that I couldn’t.”

And that’s what a great adaptation can do — it can add an element or a layer that the author may not have even thought of. “I think it’s easy for writers to feel possessive of what they do. And how could you not, right? But I was like, ‘My book is my book. It’s over here. It’s untouched. And this gets to be its whole own thing.’ And I feel like giving it that space allowed it to do cool things. It allowed it to explore many of the themes that I was looking at in the book, but from a different angle.”

Another great example of an adaptation that feels like a cover song is Anne Rice’s Interview with the Vampire on AMC. At this point, it’s basically an adaptation twice over. The 1976 novel was already famously adapted into a movie starring Brad Pitt and Tom Cruise back in 1994, but the new television series is way different.

The main character, Louis du Point du Lac, is white in the books. He owns enslaved people. In this new iteration, he’s a Black man in New Orleans in the early 1900s, which adds a whole other layer of isolation to a story about an outsider.

“It’s color conscious. It’s not colorblind casting,” says Jacob Anderson, who plays Louis. “It’s not a vain attempt at appeasing whatever people think they need to appease.”

Jacob says he was fascinated by the script, which was written by show creator Rolin Jones, who Jacob didn’t know was white. “I think he just really touched on something about Louis in that first episode. There was a verisimilitude in it, something that felt true about race and the experience of being a Black man now, as well as what it must have been like then.”

Both the book and the 1994 film were considered super queer at a time where gay relationships were rarely centered in mainstream blockbusters. But in the 90s movie, that queerness was mostly implied. None of it was actually that explicit.

“I feel like the film kind of has this sort of homoerotic subtext to it,” Jacob says. “But I think the book is queer, and almost overtly so. I think it’s all in there. It’s all in there from the beginning. I think it would be sort of awful to not have them be in a romantic relationship.”

For Jacob, this role was a challenging one. After all, Louis is a vampire. He lives for over 100 years. That’s a lot of character development to figure out how to portray. His first step, logically, was to go back to the original text.

“Initially. I tried to annotate the book. I got my highlighters out, my pencils. I thought, ‘Okay, I’m gonna just take notes about things that I think are important about the character. But to be honest, I stopped doing that because I was enjoying the book. And I didn’t want to look at it solely from a research perspective.”

For an actor in an adaptation, the trick is to find inspiration in the source text while also giving themself permission to create a new version. “If you try and please everyone, you can end up being in a really dangerous place,” he says. “I think people have a lot of focus on not isolating fans of the source material. But I feel like part of the necessity of adapting something is that you make it a second thing. Or, you know, in this case, a third thing.”

Jacob compares the process to translating something from one language to another. “There are so many different ways to look at something. And the way that you internally translate somebody’s work is completely subjective. And it’s personal, innit?”

It really is personal. Think about it: when you’re reading a book, you’re creating all these different tapestries in your own head. It’s impossible to expect a director or actor to be able to do exactly what you envisioned.

That’s why the cover song idea is so perfect. Even if it’s not exactly what you thought it should or could be, it’s still got a lot of the same notes. And that means, you can probably still sing along to it.