There was a very special reason Stephen King attended last September’s Toronto world premiere of “The Life of Chuck,” the latest picture based on one of his stories that opens nationwide today.

“He was one of the first people to see it,” recalled “Chuck” writer-director-producer and editor Mike Flanagan in a phone interview. “I’ve done a few Kings and I’m always terrified to show Steve because I know what happens if he doesn’t like an adaptation. You just have to look at Stanley Kubrick and ‘The Shining’ to see what happens if he’s not happy.

“But he loved the film. Stephen King hadn’t attended a premiere of one of his adaptations in two decades — the last one was ‘The Green Mile’ and that most beautiful moment still blows me away.

“This movie was special to him and he wanted to be in the audience when it premiered, surrounded by a thousand people watching this film for the first time.

“He loves the movie and that means the world to me, because he’s been my literary hero since I was a child.”

The Toronto International Film Festival offers just one prize: The People’s Choice Award, voted by moviegoers. It’s now a mighty omen because, tradition says, the winner goes on to be an Oscar Best Picture nominee.

“Chuck” is decidedly offbeat, not a horror story so much as an end of the world saga told, like King’s novella, in three parts, in reverse order.

“A lot of people consider Stephen King to be a horror writer exclusively,” Flanagan, 47, noted. “I’ve been reading his work my whole life and I don’t feel that way.

“I feel like Stephen King is an optimistic humanist who writes about bravery and about love. Even when he’s scary as hell.

“I thought this story was so beautiful and wise and utterly uncynical. I was just enthralled with it.”

“Chuck” with three parts is, Flanagan said, “One very specific story. It’s only the end of the world in the sense that each of us is our own world.

“The first part is ultimately about the world inside Chuck Krantz’s mind. There’s this beautiful saying, ‘When an old man dies, a library burns down.’

“That’s what this is. These three sections are individual moments toward the end, toward the middle and toward the beginning of one person’s life. And how those moments relate to each other.

“How they feed each other and create each other and how, ultimately, when we get to the end, whatever happens to us, the important thing are the connections we’ve made along the way in finding joy.

“Finding chances to create joy. Even when we feel like everything is ending.”

“The Life of Chuck” is in theaters June 6