Like most Hollywood adaptions that test a book’s formula, “Lessons in Chemistry,” a fictional drama about a gifted female chemist who reluctantly becomes a TV cooking show sensation and contends with a sexist establishment, has some controlled and experimental variables that bring changes to the story on screen.

The series was adapted from Bonnie Garmus’ 2022 bestseller of the same name. Lee Eisenberg, who developed the story for television, hopes devotees of the book will be pleased with how the show is faithful to the spirit of its source material without being a carbon copy of it.

“In the early conversations that I had with Bonnie, it was very much her acknowledging that she understood that we’re not transcribing her book into a TV show,” said Eisenberg. “The source material was so strong; the book was our bible in the writers room. We were sitting with it, we were consulting it, we were pulling lines of dialogue, we were taking descriptions and turning it into sets and locations.”

Sarah Adina Smith, who directed the first two episodes, said she treated the block of episodes as its own movie that set up the romance between Elizabeth Zott (played by Brie Larson, who is also an executive producer) and her colleague, Calvin Evans (Lewis Pullman); a relationship whose consequences will shape Elizabeth’s journey as the season plays out.

“It’s such a beloved book and one of the things that makes books so impactful is you can go at your own pace, and oftentimes you’ll put it down and, days later, you pick it up and your brain has time to sit with things and digest,” she said. “And so I wanted this show to have that sense of negative space in the way that we shot it and let us just enjoy and get lost in the love story and really feel the eternity of those moments. So that once it’s over, we’re just as gutted as Elizabeth.”

Here’s a guide to some of the changes made from book to screen.

Who is Elizabeth Zott?

The introduction to Elizabeth Zott begins differently on the page than it does on screen. The book opens with her as a 30-year-old permanently depressed single mother circa 1961, whose routine consists of rising before dawn to meticulously make her young daughter’s school lunch, which she would accompany with a note of motherly suggestions for the day, such as: “Play sports at recess but do not automatically let the boys win.” The reveal that she then sets off to her job as the popular star of a cooking TV show, “Supper at Six” comes at the end of the first chapter.

The series, meanwhile, begins by showing Elizabeth in the midst of her stardom. The hoopla leading up to a taping of her show fills the opening moments of the premiere episode, with eager audience members assembling outside the TV studio for a glimpse of the star. But it’s clear she’s no ordinary domestic idol. As Elizabeth makes her way through the studio, she asks things like, “Did you get the sodium chloride I requested?” When Elizabeth’s face finally appears on screen, nearly two minutes in, she’s just jammed a pencil in her French twist and is standing in a bubblegum-pink kitchen set, ready to be a tell-it-like-it-is guide who is unafraid to challenge the status quo for the housewives tuning in. The glimpse of her life as a mother and her melancholia come into play later in the show’s run.

“I wanted viewers to feel a sense of suspense because she has become this legendary character for so many women who love her show,” said Smith, who pitched the idea when she joined the project. “I wanted us to be, like, ‘Who is this woman? Who is the real Elizabeth Zott?’ And that we would start to unpack that as we went back in time and got to meet her. It came from that of also wanting to have maximum contrast between the star of her own show to someone who, when we cut back in time, is a lab tech who’s picking up old beakers and making coffee, and I wanted to make sure that we felt that difference really clearly.”

Calvin’s deadly run

Elizabeth is a brilliant lab tech at Hastings Research Institute — who endures harassment and disrespect by her male colleagues — when she meets Calvin, the extraordinary and lonely superstar of the same lab with a penchant for rowing. Both are socially awkward introverts who have an unpleasant first encounter: In the book, he’s unwilling to share his surplus of beakers, which she takes anyway; in the series, she sneaks into his lab to get access to ribose. Their chemistry, though, is undeniable and the two eventually find themselves working together, living together, rowing together and raising a dog, Six-Thirty, together. As their relationship gets serious, Elizabeth makes it clear to Calvin that, because of her career ambitions, she has no interest in getting married or becoming a parent, which he accepts.

But like science, the unpredictability of life takes over and the second episode ends with Calvin, while on a run with Six-Thirty, being fatally hit by a bus. In the book, Calvin is out one night walking Six-Thirty and gets run over by a police car. Elizabeth soon finds herself jobless, single and on the brink of parenthood, learning she’s pregnant after Calvin’s death.

“We talked a lot about the death, about the timing of the death, how much story we wanted to have before we got there,” Eisenberg said. “When the show begins, we’re setting up all of these different paths that Elizabeth could go down. One of them is this unlikely love story between these two people who fall in love, initially, through their passion for the sciences, and then see a depth in each other. But it’s also about grief and loss and how that person stays with you forever, but also you continue on. That was something that we discussed ad nauseam in the writers room. It was less about the details of the death. I honestly don’t remember the logistics of why we made the changes we did. It was probably what a dog is capable of doing. I think we wanted Calvin on one of his runs. It was really about the surprise of it — hopefully it’s not what you’re expecting at all.”

The beloved Six-Thirty

One of the book’s most beloved characters has four legs and an active internal monologue: Elizabeth and Cal’s dog, Six-Thirty. After flunking out of the Marines as a bomb-sniffing dog, the mixed-breed stray was roaming the streets when he followed Elizabeth home one day. His unique name commemorates the time of day when he comes into her life. And his intelligence is a perfect match for Elizabeth: He learns nearly 1,000 English words and his insightful perspective on his family’s adventures make him one of the novel’s key narrators.

“I think Six-Thirty is going to be the most controversial character for fans of the book because the thing about it is, when you’re reading a book, everybody pictures these characters differently,” Smith said. “So everyone probably had a very different idea of what kind of dog Six-Thirty was. There’s probably no way we’re gonna make everybody happy.”

In the series, he’s a goldendoodle played by dog actor Gus. He enters Elizabeth’s life after rummaging through her garbage in the alleyway of her home one night and is named for the time he wakes her up each morning.

In the episode, “Living Dead Things,” Six-Thirty’s point of view comes into play as he observes the fog of grief consume Elizabeth after Cal’s death. He’ll be voiced by B.J. Novak.