Melanie Lynskey’s hardest day on set for the new Netflix movie, Don’t Say Good Luck, didn’t involve tears or complicated monologue—it was a scene where she was asked to belt out Katy Perry’s “Firework” in a public parking lot.

“I’m petrified of singing,” Lynskey confessed to Decider in a recent Zoom interview. “I love karaoke, but I’m like the Simon Cowell of karaoke, I always say, because I tell people what songs to sing and then say, ‘That’s not your song.’”

In the film, Lynskey stars as Elizabeth, the on-screen mother of Sunny Sandler (youngest daughter of Adam Sandler, who produced the film via his Happy Madison production company), who puts on a brave face for her kid, despite her worsening cancer diagnosis. The film was directed by Julia Hart, with a screenplay written by Hart, Jordan Horowitz, and Laura Hankin; and the story was inspired by Hankin’s real-life experience getting cast in the lead of her high school’s musical, at the same time that her mom was battling terminal cancer.

As a mother herself, Lynskey was drawn to Elizabeth’s “pure maternal love,” and has a easy, charming rapport on screen with the youngest Sandler. The Emmy-nominated New Zealand actor spoke to Decider about working on the film; getting over her fear of singing; and her emotional final day on the set of Yellowjackets, which wrapped filming it’s fourth and final season earlier this month.

DECIDER: Did you get a chance to speak to writer Laura Hankin about her own mother, who was the inspiration for this story? What was your initial impression of the character of Elizabeth?

MELANIE LYNSKEY: I did get to speak to Laura. She was on set and she was so wonderful. She’s such a sweet person. That was the first thing that I really loved about the script, was how specific it felt. I was like, this feels real. Then to find out that it was actually her true story was really beautiful. Elizabeth was just so loving and so good, without being boring. I responded to that. I liked that she felt like a fully-realized human being, but was also just pure maternal love. 

You and Sunny Sandler are so natural and funny together. Talk about the first time you met Sunny, the conversations you had with her about your characters, and working with her on screen. 

The first time I met her was in the production office. She came in, and she was so disarming, sweet and such a genuine teenager. I had seen her [You Are So Not Invited to My] Bat Mitzvah movie, and I thought she was great in it. But to meet her and see how completely unguarded and genuine she is was a real relief. She’s a real sweet human being. And then getting to know her, it’s just been a joy. She’s so caring, so thoughtful. She’s just raised well. They’re a good family, she’s a really good kid. She worked so hard. She would have a day off, and she would be in musical theater rehearsals—just working so hard all the time. I just really appreciate her, and was really grateful that we had a true bond with each other that we didn’t have to fake. 

The first time I really fell for your character was when Elizabeth is belting out “Firework” by Katy Perry in the parking lot. You just keep going! Can you tell me about filming that? 

It was a nightmare. [Laughs.] The thing that made it okay was, they had a vocal coach, Fiora, who was working on the movie, helping the kids with all of their stuff. She’s absolutely incredible. Fiora came and did some work with me. I’m petrified of singing. I love karaoke, but I’m like the Simon Cowell of karaoke, I always say, because I just tell people what songs to sing and then say, “That’s not your song, you need to do this song.” But I don’t really sing myself, I’m very scared of singing.

The thought of being in a parking lot, belting out “Firework,” was so difficult. Fiora got me to a place where I felt so comfortable. There were so many people standing in the street, watching ,because everyone wanted to see if they could see Adam. I was okay to just do it, and it’s a miracle. She’s a miracle worker, truly. 

You sounded great!

That’s not true, but thank you. I just needed to be not afraid. I think that came across. That’s what I kept telling myself. I was like, “It doesn’t have to be good ,and it shouldn’t be good.” It’s always a little weird when someone’s not a singer, and then they sing and it’s perfect. You’re like, what? 

I also love the scene where you and Sunny are trying out Southern accents. You’re already acting in your not-normal accent, so I’m wondering what filming that sequence was like, adding another layer to the accent work.

My regular American accent that I do is so second nature at this point. It was just fun. It was fun to do that. It was to do anything with Sunny—days working with her were always just so easy. She made it very easy.

How do you feel when fans tell you they have no idea you weren’t American because it sounds so natural on you, the accent? 

Oh, thank you. Yeah, people do that all the time. People are always confused and think that I’m like putting on some kind of voice or something like that. I feel lucky that I still have my New Zealand accent, because I’ve lived in America for so long.

Elizabeth works so hard in the movie to put on a happy face and hide her pain from her daughter. As a mother yourself, do you relate to that instinct, and do you think Elizabeth was right to do that?

That was something we talked about a lot on set. It’s impossible to know, I think, until you’re in that situation. We’re very honest with our daughter. We talk to her about everything. She talks to us about everything. So it’s a little hard for me to imagine… but also you do have a protective instinct. You do want to shield your kids. I understood it, even though I don’t know if that would be exactly what I would do. 

I’m wondering if while you were making this movie, if any feelings about motherhood came up, like did it reaffirm any beliefs you had about being a mom or make you rethink anything? 

For me, being a mother is just the greatest thing I’ve ever done. I had my daughter when I was 41, so I had a lot of a life before I had her. I feel like a different person, you know? She’s just my whole world. I love her so much. I’m obsessed with her. She knows that. I think having that to hold on to when you’re playing a mother, and realizing the things you love about your child are so specific and unique to them. And they’re also things that you’ve been seeing in them since they were babies. It just helps so much with a performance when you are playing a mother, and you know what the experience is like. 

Tell me a little bit about working with Adam Sandler, who’s a producer on this film, and your take of how the whole Sandler family works together for these Happy Madison productions. 

He’s a wonderful producer. He was very a nice mix of hands-on and hands-off. Sunny’s such an incredible actress, and she was very much doing her own thing. There was nobody stepping in with anything to do with anyone’s performance. He was very much in charge of what the tone was going to be, and also setting the tone on set, in terms of like being a wonderful human being—being very kind to everybody, being very personable. Within their family, they’re all such great people. There’s no room for bad behavior. It really set a lovely tone. I do understand why people go back and work with him and the company time and time again, because it’s just very relaxed, very easy. I see why people are so loyal because, they’re great people. Jackie’s amazing. Sunny’s amazing. Sadie’s amazing. They’re just a really good family. 

Have you wrapped on filming the fourth and final season of Yellowjackets? And if so, without giving too many details, can you say what kind of scene was the last one that you filmed? 

I have wrapped. I finished a week and a half ago. I filmed a scene with Warren Kole, who plays Jeff. That was the last scene we filmed, and it was the scene, on the last day of shooting. So it was a wrap for the entire series. It was crazy. I mean, they said, “That’s a wrap on Yellowjackets!” Everybody was clapping and cheering, and Warren and I were just sitting there, just staring at each other. It was very hard for us to process the fact that that was the last time. He’s such a treasure to me. I just love him so much. I said to him, “I don’t think we’re going to get to work together again.” And he was like,”I know.” It just has been such a joy. He’s just one of the greatest scene partners I’ve ever, ever had in my life.

We had a lot of speeches. Different crew members gave speeches—producers, and our creators and crew members were shouted out in particular ways. Trophies were handed out. People were crying. I was crying, so much. I got a little trophy that said “Best Person Ever,” from the crew, which was the greatest trophy I’ve ever won. It was such an emotional day. It’s very weird. It’s been such a big part of my life. My daughter was 11 months old when I did the pilot, and now she’s almost eight. The not going back to it is just sort of crazy.