How the 'Girl in the Box' Became a Lifetime Movie – Nearly 40 Years After Her Kidnapping Â

The nightmare that Colleen Stan endured for seven years – when she lived in a box for 23 hours a day – seems almost too horrific to be true.

But it is true, and this Saturday at 8 p.m. EST, Lifetime will air Girl in the Box, a two-hour movie about her kidnapping and capture by Cameron and Janice Hooker. Janice later testified against Cameron in exchange for immunity. He was convicted of rape and kidnapping and   sentenced to 104 years in prison in 1985.

How did her story become a movie nearly 40 years after she was first captured?

The film's writer/director/executive producer Stephen Kemp met Stan a few years ago while working on a documentary about the case and was just "struck by both her and her story," he tells PEOPLE exclusively.

"I was very surprised it hadn't been sampled as a drama before, so I began the process of developing the script," he says.

Still, he had reservations about the project.

"I was actually quite nervous about the idea of trying to tackle it because it does have some very dark aspects to it," he says. "But actually it's also the story of a survivor and someone who manages to overcome a terrible ordeal, and comes out the other side of it."

He tried to portray the positive aspects of the story as well as the obvious dark ones.

"I think the film itself is in some ways quite an uplifting film despite having some very dark things in it," he says.

He spends most of the film inside the seven years of her captivity, he says.

"Within those seven years a huge amount happened," he says, "and it was a big challenge to try to capture all the twists and turns and things that happened into a 90-minute film."

As for Stan, 59, she still hasn't seen the movie herself, though she watched the filming back in March in Prescott, Arizona, describing the experience as "really cool."

For more on Colleen Stan's incredible ordeal, escape and survival, pick up this week's issue of PEOPLE, on newsstands Friday.

"I got to actually meet the main actors," she says. "I didn't even know that Zelda [who plays Janice] was Zelda Williams, and Robin Williams' daughter," she says. "I just found out like a month ago.

"I also got to meet Addison Timlin, the little lady that played me, and Zane Holtz, the guy that played Cameron," she continues.

"Zane was really afraid to meet me," she says. "He told Addison, 'She's going to be mad at me. I'm afraid to meet her.' I told Addison, 'You tell him I want to meet him and no, I am not angry at him.'

"Then I met him and I said, 'Hon, somebody had to play him.' I said, 'I feel bad for you that you had to play this guy.' "

"The last night, after they were all wrapped and done shooting, we all had dinner together at a really nice restaurant in Prescott," she says. "Stephen Kemp was there and a lot of the production crew as well as the three main actors. It was kind of a fun thing that I got to go."

Kemp says he hopes she likes it the movie.

"I think Colleen herself is quite an inspirational character when you meet her," he says. "And I think when you see the film, you'll understand just how incredible it is that she survived what she went through and has managed to rebuild her life afterward."