The actress talks to ET about the final episodes of the Netflix series.
Spoiler alert! Do not proceed if you have not watched Part 2 of Firefly Lane's final season.
Picking up where Part 1 left off, the back half of season 2 chronicled Kate's harrowing journey as she battled an aggressive form of breast cancer and finally mended fences with her best friend, Tully. But when Kate's cancer returned, she was faced with the reality that her life was coming to an unexpected close. By the end, Kate had come to peace with her limited time left, spending her precious last weeks writing her life's story in the form of a book, appropriately titled Firefly Lane, and leaving her loved ones with details on her wishes for the funeral and beyond.
As Firefly Lane star Sarah Chalke shared with ET's Deidre Behar over a Zoom interview, exploring Kate's cancer battle in Part 2 and portraying it onscreen was nerve-wracking. "Obviously [I] read [Kristin Hannah's] book and knew the ending and part of me was nervous about that experience and what that was going to feel like to play all of those scenes," the actress reflected. "But I thought it was so beautifully written. It was a really challenging but also great experience."
There was one scene from the final batch of episodes that was the most challenging for Chalke to film -- and it "caught [her] off-guard." It was the moment where Kate had the difficult conversation with Tully that she had come to terms with her cancer. "Sometimes a scene ends up taking a direction you don't expect and one that you thought was going to be not as challenging was the most challenging for me. The hardest scene to shoot was the scene where Kate accepts that there's nothing more that they're going to do. And then she has to tell that to Tully," Chalke recalled.
"It just ended up being a really emotional scene. It's every parent's greatest fear that you won't be able to see this all the way through and watch your kids grow up, and there's just so much pain in that scene. And then there were two things happening -- both Kate accepting it and her having to relay it to her best friend," she continued. "Michael Spiller, who I've known for 20 years, he was directing that episode... Right after we finished shooting that scene, it was the end of the day of shooting. They're like, 'OK, wrap. Now, Sarah, let's go record the voiceover for the funeral.' So the letter that Kate reads to Tully at the funeral -- the very last scene of the series -- we had to record right after that because they needed it to play for Katie [Heigl] when she's going to shoot her scene... She's like, 'Take care of Mar for me.' I was like, [takes a gulp]."
Adding to the enormity of those moments was the amount of time Chalke invested in the show. "We've spent so long on this show at that point and gotten very close with a lot of the crew and nobody's life is not touched by cancer," she said. "So when you're doing these scenes, you're looking out into the eyes of all of these people who you've become close with who've had their own experiences and so it ended up being quite an emotional couple of months."
Chalke credited Tully and Kate's life-long friendship -- even though they went through a period of time when they were estranged -- for being a positive force and guiding light during Kate's difficult cancer battle. (Creator/showrunner Maggie Friedman told ET she "didn't want to torture people too much" by keeping the BFFs apart for longer than they had to be.)
"It's so beautiful how it's not this glossy, perfect friendship, but it's all the real, hard stuff that they went through and their friendship was so hard won," Chalke said. "For Kate, she probably could have gotten over the situation sooner if it had been something between her and Tully. Because it involved Marah, she didn't know how to move past it. But then at the end of the day, when she was diagnosed with cancer, Tully was the main person that she wanted by her side. And Tully was right there for her. I think it just shows they're family."
While Kate's death in the finale was a heartbreaking end to her story, Chalke said she "loved" the way the series wrapped up -- with Tully dancing to ABBA's "Dancing Queen" outside Kate's funeral after going through her friend's most prized possessions.
"I loved the way that Katie played it. There was so much pain and then there was also this incredible joy of playing this song and dancing to it, and I love, creatively, that you never go into Kate's funeral," the actress noted. "You're just staying outside with Tully. I thought that was such a really interesting and unique choice and just the fact that Kate had really thought so hard about what this was going to be like for Tully and tried to find a way that she knew she would be able to cope with the best."
As for the flash-forwards to Marah's wedding in 2016 to her doctor girlfriend, Chalke described the scene as "hopeful." "Kate and Tully were so close and they're such amazing friends -- to a certain extent there's a piece of Kate that lives on through Tully and that lives on through Marah. And the fact that they were the two that were there for each other on that day, I really loved it," she said of the pair.
Of course, there was a brief moment where it seemed as though Kate may have prevailed through her cancer recurrence, only for it to be revealed that it was Tully imagining what Kate would have said to her on Marah's wedding day. Chalke acknowledged a part of her hoped her character would have made it out the other side OK "because I love the job." "There's that piece of it where I'm like, 'Keep going,' but I do think that in terms of the show, I loved how it ended."
Though Firefly Lane marked the culmination of Tully and Kate's "complete story," as Friedman put it, a follow-up novel by Hannah was released in 2013 following Tully and Marah's lives as they grieved Kate's death. Could there ever be a chance for a continuation of the story? Chalke didn't shoot down the idea, but also didn't offer too much hope of that coming to fruition. "I don't know. I love the whole experience. I love the characters. I loved all of it. So I would [be in for a follow-up], I just feel like I don't know just because it did follow exactly how it went [in the book]," she explained.
Even if this is it for the Firefly Lane ladies, Chalke expressed gratitude to the fans for sticking by Tully and Kate.
"Thanks for watching it. We had such an incredible time making it and we're so grateful. People showed up to watch it and one of the coolest parts was hearing from people after, like, 'Oh my god, it made me reach out to my best friend and made me reach out to this family member and made me think about how that's kind of all that matters,'" Chalke said. "If that was people's takeaway, then that's so cool."
Firefly Lane is now streaming on Netflix.