It’s been 20 years since Stephen Chbosky released his debut novel, “The Perks of Being a Wallflower,” to worldwide praise and adoration. He’s been busy since then — scripting the live-action “Beauty and Beast,” directing the adaptation of another beloved book “Wonder,” and even adapting “Perks” into an equally acclaimed feature film. But he always intended to write another novel.

“My experience with adapting my own book and directing ‘Perks’ was so gratifying, I knew I had to do it again,” says Chbosky. “But that would necessitate another book. So I had to write it.”

Chbosky is calling from Massachusetts, one stop on a busy tour that begin on Oct. 1, when his new novel “Imaginary Friend” was released. At first glance, fans might be caught off guard. Where “Perks” ran around 250 pages and was a grounded high school coming of age story, “Imaginary Friend” clocks in at over 700 pages and marks new territory for the writer: horror.

“Imaginary Friend” tells the story of 7-year-old Christopher who moves with his mother to a new town when she flees an abusive ex. After Christopher goes missing for six days, a series of strange occurrences take place, including a lottery windfall and Christopher’s sudden intelligence. To say any more would spoil the many surprises in a book filled with imagery and themes that run the gamut, from biblical references to fairy tales.

But even in the horror genre, there is the DNA of a Chbosky project: complexly drawn characters, deep friendships and the bonds between family. Having spent the last 10 years percolating the ideas in “Imaginary Friend,” the author knows horror works best when audiences are truly invested in the characters. Chbosky scares because he cares.

You’re on tour with your first book in 20 years. How have things changed?
I guess the fact that I’m doing a tour is the big change. When “Perks” was released, it was a midlist trade paper original. I had two events in New York, organized with my friends. Then I got in my mom’s old Saturn car and drove around on my own tour, crashing on couches. There was no glamor but I was young and I didn’t care. Now I have a great team; Grand Central Publishing has been fantastic and it’s going all over the world, including Paris and London. It’s much easier to get noticed on your second book than your first.

What was the initial impetus for this story?
I think we all remember a moment in childhood where you lay on the ground and look up in the sky and talk about what the clouds look like. The book began with the idea of what would happen if a little boy looked up into the clouds and realized that for two weeks, it was always the same face looking at him?

So it was a visual idea first?
Because I’m a movie person, I think in moments, and they’re often cinematic. So I thought of this moment where he looks up, sees the face, and says, “Hello, can you hear me? If you can hear me, blink your left eye.” And the cloud slowly blinks its left eye. And then unblinks it, floats away, and the boy follows the cloud. The metaphor of following the cloud stuck with me. So over the last 10 years, I followed it.

This is a new genre for you but you’ve been interested in writing in horror for some time?
Always. I love the horror genre, Stephen King is my favorite writer of all time. John Carpenter’s “Halloween” and “The Exorcist,” “The Shining,” “Sixth Sense” — these are some of the all-time greatest stories. “Halloween” would beat out a whole lot of best picture winners in my book. So I’ve always wanted to try this. And I found it very gratifying. It was challenging and interesting to try and write in the emotional style people have become accustomed to in my work, but in this new genre.

Have you encountered any resistance or surprise from people about the change?
People expecting “Perks 2” might resist the genre change but what’s been very gratifying is for the most part people who love “Perks” have loved “Imaginary Friend” because they see the same emotional sensibility. And the same feel for character, the same empathy — almost supernatural empathy. They’ve been very supportive and positive.

Since you’re a filmmaker also, the inevitable question is: will you be adapting this for the screen?
I am. I don’t know if it will be a movie, a miniseries – I’m open. As I’m going, I keep asking myself: Can I really live without this moment? In some cases, it’s an easy call. In other cases, not so much. My guess is that at the bare minimum, it will be two films.

Do you have a preference between filmmaking and writing?
Writing a novel is the loneliest life I’ve ever known. I couldn’t do it forever; I don’t know how people like Stephen King do it. It is so demanding in terms of time alone. I greatly prefer a movie set where there’s other artists you’re collaborating with and when you’re stuck, it’s not just you and your brain.

What scares you?
The idea that there is something else and that it’s not always benevolent. My family rented a house in New Jersey online, so we only saw pictures. We walked into the house and I swear to God, I said, “What is wrong with this place?” It was just in my skin instantly. And when you have that feeling and you see your daughter turned to the corner like in “The Blair Witch Project” holding up her finger admonishing something that’s not there going: “No. No.” …Well, you spend that night at the Best Western and you eat the $3,000 prepayment. Then you’re not remotely surprised the next time you pass that street and the house has been torn to the ground.

You mentioned Emma Watson helped you with this story?
We were filming “Perks” and I was telling her the story of “Imaginary Friend.” I had started writing the book, but was only a little into it. I had her on the edge of her seat and I got to my original ending and I presented it … and I swear she looked at me and went: “Huh.” I went, “What, not good?” She’s polite to the end and would never tell me it was bad but I could tell it was a complete letdown. She studied English at Oxford and Brown and is one of the most well-read people I know, so I went back to the drawing board because of Emma Watson specifically. The last two people thanked in the acknowledgments are Emma Watson for the ending and Stephen King for everything else.