Warning: This article contains major spoilers for Firefly Lane season 2. When Firefly Lane star and executive producer Katherine Heigl began working on Netflix’s highly anticipated second season, there was one element of the story that was a “hard pill to swallow.” It also happened to be the biggest plot line of the series, the answer to the burning question of what Tully did that could cause such an irreparable rift between lifelong friends.

The script, much to Heigl’s apprehension, deviated significantly from the source material—two novels by the bestselling author Kristin Hannah. Heigl “struggled with this,” she tells StyleCaster over the phone. “I’m such a big reader and I treat authors like rockstars. To me, you don’t mess with their stuff. But I’m not I’m not always right. Well, that in many things, but I really struggled with this with Maggie [Friedman, the show’s creator].”

Katherine Heigl, Firefly Lane

Courtesy of Netflix

The story follows inseparable yet unlikely pals Tully Hart (Heigl) and Kate Mularkey, played by Sarah Chalke, with whom Heigl has found real-life friendship. “I don’t have to act when I’m with Sarah, I get to just love her from her effusively,” she says. Viewers bear witness to Tully and Kate’s friendship over the course of 30 years, from teenagers in the ’70s to adulthood in the early 2000s. While they have totally opposite personalities, they possess a seemingly unbreakable bond forged in life experience. That is, until the cliffhanger of season one, where we learn Tully has done something truly terrible. “No one wants you here,” a brash Kate tells her in the closing minutes of the final episode. “When I said I could never forgive you for what you did, what did you think that meant?”

In the books, it’s because talk show host Tully brings Kate on as a guest for The Girlfriend Hour, under the guise of mending Kate’s strained relationship with her teenage daughter, Marah. It turns out to be a special on oppressive parents, humiliating Kate as a bad mother on national television. This is not what happens in Netflix’s adaptation, part one of which—nine episodes—is available to stream now. We once again jump between teenage Tully and Kate (masterfully played by Ali Skovbye and Roan Curtis respectively) and the events leading up to their fractured friendship. Accountability is the name of the game and we watch as a well-intentioned Tully repeatedly refuses to say “sorry” when their friendship de ella is tested by her mistakes de ella. It’s not until episode seven that we finally learn Tully’s unforgivable act from her and, be warned, MAJOR spoilers ahead.

Firefly Lane

Courtesy of Netflix

While Kate and Johnny Ryan (Ben Lawson) attempt to rekindle their broken marriage, Marah spends the weekend with her godmother, Tully. The duo tries to decode messages from Marah’s love interest to her and ultimately, Marah gets asked on a date to see The Notebook. She’s grounded, though, and begs Tully to go. “Mom won’t know,” she pleads. A hesitant Tully eventually agrees, convinced by Marah that it’ll be “totally safe” and above board. “I want you back by 10 pm, not a minute later,” Tully compromises and decides to unwind with a few glasses of wine. When she doesn’t return home by the prescribed time, Marah calls Tully in a panic. “I’m at a party at some U-dub frat,” she cries. “We met some boys outside the theater and they invited us to a party on campus.” Tully senses Marah’s urgency for her and without hesitation, goes to pick her up. It’s on the drive home with Marah in tow that Tully’s car is T-boned; Struck by another driver running a red light. Marah is admitted to the hospital with serious head injuries while Tully, who scrapes through with comparatively minor wounds, is issued a DUI and presumably faces criminal charges for reckless endangerment.

Heigl is defensive, though conflicted, on Tully’s behalf. “Maggie really figured out how to create this weird moral dilemma that I still don’t know how I feel about it. I think people when they watch it, they’re going to be torn. You’re going to have the Team Tullys and Team Kates,” she says. “As Tully’s defend, I feel like this is bullshit. Why is Kate not speaking to her over this? It was not her fault. Tully was trying, once again, to do the right thing. She made some stupid choices by letting Marah go at all and by not calling Kate and getting in a car after having a couple of drinks. Those were very stupid choices. But again, she didn’t run the red light.” As a mother of three, Heigl then puts herself in Kate’s shoes from her. “Then I look at Kate’s perspective of her. And I don’t know if I could forgive someone for putting my kid in harm’s way like that. It’s so murky.”

40 felt like freedom to me and I don’t know exactly why except that I felt now too old to continue to not know who I am but I’m young enough to still change

Fans will have to be patient once again, as part two—the final five episodes—will drop on Netflix on June 8, 2023. As part one closes, we’re left with another heartbreaking cliffhanger and the big question of whether Tully and Kate will ever be friends again is suspended. “I wish they were just dropping them all at once,” Heigl says of the time gap between parts one and two, “because I’m dying to see them and I’m dying for everyone else to see it because it’s so important, in my opinion, to the story.”

Firefly Lane is arguably Heigl’s most important work. It certainly feels the most “her de ella.” At 44, the actor who made a name for herself in the longstanding medical drama Grey’s Anatomy and then in romantic comedies like 27 Dresses and knocked up, Heigl has found self-assuredness in recent years. We couldn’t help but ask her about a line from episode five of Firefly Lane season two that felt particularly poignant at this time in her life. “When you’re young, there are so many possible roads to go down,” Tully’s hippy mother Cloud tells her her 20-something daughter. “You have the whole map in front of you and then, sometimes in your 40s, you realize there are no more U-turns. A bunch of roads are closed and half of them are in the rear-view mirror.” There are two ways to interpret this, of course. “Way to boom me out,” Tully replies.

Firefly Lane

Courtesy of Netflix

For Heigl, who pursued a career in an industry “that really takes it all,” she likes to see the proverbial glass half-full in this speech and that includes embracing a totally new road to go down. At a time when every celebrity seems to be launching a skincare brand, Heigl has followed a true passion, that of animals in the form of her pet nutrition brand Badlands Ranch. “My mother and I’ve had an animal advocacy foundation for almost 15 years now. So, we are passionate animal people and we have been working really hard to try to save them.”

It’s not that she doesn’t have misgivings about the choices she’s made over the years, however. “After my first child, I was still hustling. Still hustling, still hustling, and I have regrets about that. I missed a lot,” Heigl reflects. “[But] 40 felt like freedom to me and I don’t know exactly why except that I felt now too old to continue to not know who I am but I’m young enough to still change.” She continues: “It gets clearer to me every year. I feel more and more comfortable with who I am… I still think it’s important to change your mind change and see things from other people’s perspectives. But it’s not this desperate thing. It’s more of a flow. It’s more peaceful. It’s being more at ease with myself.”

Firefly Lane season 2, part one is available to stream on Netflix.