Judy Greer has teased 'The Long Walk' will be a "dark, but beautiful" adaptation of the original book.

The upcoming movie – which is based on Stephen King's 1979 horror novel of the same name – will follow a brutal "competition" where 100 teenage boys are forced to walk until all but one have collapsed, and now the 49-year-old actress has teased the upcoming film will do justice to the book's dystopian tale through the "stunning" performances of her co-stars.

In an interview with Collider, Greer said: "It’s a dark story about a competition show. But it’s beautiful, and the performances that I got to watch when I was on set were stunning."

The 'Halloween' actress - who stars opposite Cooper Hoffman, David Jonsson and Mark Hamill in the flick – quipped that her husband Dean E. Johnsen was shocked by the book's story.

She said: "My husband just read the book, and every night in bed, he’d be just turning a page going like, 'Oh my God, oh my God.'

"I’m like, 'I know. I was telling you every day when I was shooting.' He’s like, 'Yeah, but it’s really dark!'"

'The Long Walk' also features a handful of young actors including, Garrett Wareing, Tut Nyuot and Charlie Plummer, who Greer dubbed “incredible”.

The '13 Going On 30' actress added that she felt it would be "so nice" for audiences to become completely engrossed in the film and its characters because there won't be too many Hollywood A-Listers pulling attention away from the story being told through their star power.

She said: "Personally, it’s so nice sometimes to see movies cast with people I don’t already know because I can still lose myself in the story, you know?

"Not like I watched the movie, and I’m like, 'Oh, I need to call her.' I’m like, 'I don’t know who they are, and they’re amazing.' That’s kind of how I felt when I was on set. These young guys are just incredible."