‘Lessons in Chemistry’ Showrunner Created “The Book of Calvin” Because Lewis Pullman Was Just Too Good

The penultimate episode of Apple TV+‘s Lessons in Chemistry is called “The Book of Calvin” and explores the backstory of one Dr. Calvin Evans (Lewis Pullman). While Lessons in Chemistry Episode 7 “The Book of Calvin” definitely weaves in moments readers of Bonnie Garmus’s bestselling book will recognize, it also boldly reframes key moments from the show’s first two episodes from a whole new perspective: Calvin’s. So far, Elizabeth Zott (Brie Larson) has taken center stage. We watched as Elizabeth fell in love with the handsome, idiosyncratic genius, letting her defenses fall just so Calvin could pick her up. When Calvin dies in a tragic accident, we stay with Elizabeth through her crippling grief and the birth of their daughter, Mad (Alice Halsey). As Elizabeth transforms into a popular cooking show host, her precocious grade school-aged daughter starts looking for answers about her father. Which leads us to… “The Book of Calvin.”

As it happens, though, “The Book of Calvin” wasn’t originally in showrunner Lee Eisenberg‘s outline for Apple TV+’s Lessons in Chemistry. Instead, the idea to focus a whole episode on a character killed off at the end of Episode 2 came from how darn good actor Lewis Pullman was in the role of Calvin Evans.

“The end of [Lessons in Chemistry] Episode 2 is Calvin’s death and that changes things in a cataclysmic way. The audience thinks they’re watching one thing, and then the show has twists and turns and has surprises. Very much the way that the way that life is,” Eisenberg told Decider. “And as we started watching the dailies and started seeing the cuts for the episodes, I was so taken with Lewis, just as a performer. I thought he really explodes off the screen and, selfishly, I was like, ‘How do I get more of him in the show?'”

Eisenberg said that there were two quirks of Lessons in Chemistry‘s scripts that helped him come up with the idea of “The Book of Calvin.” One was the way in which the show structurally handled flashbacks. It opened up the door for the show to flit back in time to when Calvin was still alive. The other secret boon? The fact that Eisenberg and his writers’ room was scripting the series during production.

“We were writing as we were going, which was very stressful and had its own challenges. But the benefit of it was we were able to kind of change things quickly,” Eisenberg explained. “So when we saw how strong Lewis was, we really started talking about the end of the season and how we wanted to end things and what the audience wanted to see and what I wanted to see as a fan of the material.”

As a fan of Bonnie Garmus’s novel, Eisenberg knew that there was “a reference to Calvin writing letters back and forth with another character named Wakeley.” While it’s a relatively short section, he thought, “Wow, what an opportunity. Maybe that’s the way in to learning a little bit more about Calvin.”

“We felt like taking an episode and really devoting it to Calvin. And I called the episode ‘The Book of Calvin.'”

Eisenberg shared that while he was a little bit frightened to show the parallel version of Calvin and Elizabeth’s romance from Calvin’s perspective, it nonetheless “compelled” him. The end result might veer from the source material, but it adds more depth and nuance to Calvin Evans and his connection with Lessons in Chemistry heroine Elizabeth Zott.

The series finale of Lessons in Chemistry premieres on Friday, November 24 on Apple TV+.