Winona Ryder is no stranger to the spotlight — or to grief. On Stranger Things, which premiered on Netflix in 2016, Ryder plays Joyce Byers, a grief-stricken suburban mother coping with the sudden disappearance of her young son, Will Byers (Noah Schnapp), in the show’s first season. When it came time to bring Joyce to life, Ryder didn’t need to look far for inspiration — she knew a family that experienced a similar loss.

While chatting with Interview magazine for its winter issue, the Stranger Things actress spoke of a young girl named Polly Klaas, who went missing in Petaluma, Calif., where Ryder was raised.

“I had this experience when I was in my early twenties: There was a girl from the town that I grew up in,” Ryder said. “Her name was Polly Klaas, and she was kidnapped. I knew her family.”

Klaas, who was 12 years old, was kidnapped at knifepoint by a man named Richard Allen, who entered Klaas’s mother’s home during a slumber party on Oct. 1, 1993. Ryder told Interview that, at the time, she was doing “whatever I could to help this family” and keep the story in the news, even offering a $200,000 reward for Klaas’s safe return. But the search for Klaas came to a tragic end two months later, on Dec. 4, 1993, when her body was found buried near Cloverdale, Calif., about 35 miles north of Petaluma.

“When you’re around that kind of tangible grief, it’s otherworldly,” Ryder said. “She wanted to be an actress, and her favorite book was Little Women, so that was a big reason I did that movie and dedicated it to her.”

Because of her connection to Klaas and how affected she was by her disappearance, Ryder voiced concerns about the Stranger Things plot. She wanted the show’s creators, Matt and Ross Duffer, to understand the gravitas of a missing child case and to make sure they handled it with care. Ryder also consulted Klaas’s father, Marc, on how to approach her character.

“I was actually really freaked out with Stranger Things, because I wanted them to know how f***ing serious that is, and that you can’t use disappearances as a tool to advance — it feels very personal,” she told Interview. “I also talked to Polly’s dad, and a lot of my performance in that first season was connected to him. I worked really, really hard that first season, and then the show took off in a way that I have certainly never been a part of.”

Ryder added, “I remember having a moment that was really liberating and relieving, when I realized the show was no longer about me.”

Season 1 of Stranger Things revolves around Will’s disappearance and the desperate attempts made by his mother, played by Ryder, and his band of friends, Mike Wheeler (Finn Wolfhard), Dustin Henderson (Gaten Matarazzo), Lucas Sinclair (Caleb McLaughlin) and Eleven (Millie Bobby Brown), to find him. In channeling the raw emotions of a parent grieving the loss of a child, it wasn’t long before Ryder grew close to and protective of her young cast.

“I was watching these kids at this tender age getting enormous attention that would be overwhelming for anybody and feeling really protective and concerned, because I went through it,” Ryder told Interview. “But it wasn’t similar at all, because technology and social media have completely changed everything.”

The first volume of the fifth and final chapter of Stranger Things debuts on the streamer next week, marking an end to nearly a decade of working with Wolfhard, Matarazzo, McLaughlin, Schnapp and Brown. It’s an emotional thing for Ryder to reconcile, especially given how tightly knit the cast has become.

“I feel like this season I got to spend time with all of them, which was incredibly special. They’re, they’re just … I’ll get emotional … They’re just ... I will always love them forever,” Ryder said during the Stranger Things Day celebration in Los Angeles on Nov. 6.