I’m always fishing around for books for this column, and, at the National Book Awards ceremony in November, I was sitting next to agent Eric Simonoff, who told me: “Imaginary Friend.” I was on it.

Stephen Chbosky’s new novel, his first since 1999’s megaselling The Perks of Being a Wallflower, is a work of literary horror publishing in October from Grand Central. A single mother fleeing an abusive relationship settles in a small town with her young son. The boy, Christopher, disappears into the local woods and reappears six days later, unharmed but changed. From a face in a cloud, he hears a voice warning him of a future disaster and setting off a classic battle between good and evil.

The book runs 700 pages, and when I talk with Chbosky, who is nothing if not animated, he says, “When you read the last line, there’s only one question: where’s the sequel?”

The excitement around Imaginary Friend—including the rumored $3 million it fetched in a heated auction after Simonoff batted away preempts—is intense, and even the coming together of author and editor has a touch of the supernatural.

Publisher Ben Sevier acquired the book with senior editor Wes Miller, who moved to Grand Central from Little, Brown’s Mulholland Books in 2016 to focus on mystery and thriller titles and big franchise authors. Turns out Miller is almost an acolyte of Chbosky. “I’m 33 and read The Perks of Being a Wallflower as a teenager,” he says. “It was as amazing for me as it was for a whole generation. I gave it to all my friends. And I reread it every year.”

Meeting a childhood hero was one thing, Miller says, but working on Imaginary Friend was even more thrilling. “This book is such an evolution for Chbosky as a writer. It’s a completely different genre, but it still has the perspective of youth. There’s a thread of sweetness, with these wonderful characters in a sweeping story. The lines just jump off the page.”

Grand Central began hearing rumors about the book from literary scouts in January 2018. Miller says he reached out to Simonoff (they work together with authors Douglas Preston and Lincoln Child) and asked to see the manuscript for Imaginary Friend, which Simonoff had just sent out. Actually, what Simonoff was offering was half of the manuscript, about 100,000 words. (Chbosky says the idea for this tactic came from his experience in Hollywood, where he’s spent the years between the two novels: “I know about cliffhangers—I didn’t want to reveal the ending.”)

Miller read it overnight; Ben Sevier read it; editor-in-chief Karen Kosztoinyik read it. “We knew we wanted it,” Miller says. “It was such a work of imagination. Ben was ready to bid.” The auction went on for a week and a half, officially ending in early February. “They would come back to us once, twice a day,” Miller recalls. “It was like a poker game!”

Chbosky flew to New York to take a series of meetings, and that’s where the magical aura around Imaginary Friend really kicked in. Recounting the day Simonoff and Chbosky came into the Grand Central offices, Miller talks about “having a feeling that everything in my career had brought me to this meeting.” He adds, “I had a sixth sense suggesting it would work out. Eric arrived first, and, while waiting for Stephen to arrive, I had an epiphany: I was meeting not only the author of Perks but the author of Imaginary Friend.”

Chbosky had a similar reaction. “Of the five meetings we took in New York, Grand Central was the last,” he says. “I had an instant connection with Wes, like the one I had when I first met Eric. Everyone was wonderful, but I had an instinct about Wes. I knew he would help me do my best work.” The deal was signed in April 2018 for North American rights, and Miller got the second half of the book.

Chbosky went to film school; he never took a writing class. “The Perks of Being a Wallflower just came,” he tells me. “It was a very personal novel.” And after Perks, which he says has sold five and a half million copies worldwide, he tried everything: TV, directing, screen writing. “If I had a time machine, I’d go back and tell myself not to spend all those years making films, but I don’t have a time machine. I realized that, after 15 years, the most satisfying thing I’d done was adapt Perks.”

Nine years ago, Chbosky started writing Imaginary Friend. He found a doodle of a cloud and thought about looking up at the clouds as a child, and it made him wonder, “What if there were a face in the cloud, but always the same face?”

“I knew it would be horror,” Chbosky says, “but I’ve spent my career dealing with emotional stories—creating characters an audience can connect with and then putting those characters in extraordinary circumstances.” He started the book when he was single, he says, and has since married and had two children. He tells me about losing his son for minutes on a visit to Sea World and the primal fear that he experienced. “I use those feelings,” he says. “In Imaginary Friend, I wanted to celebrate the protective instinct of a mother with her child.”

Most of the editing was done face-to-face. “Stephen would be in town from California, and I would block out my schedule,” Miller recalls. “And we’d get together in the library room where we’d had the original meeting. Stephen would sit in the same chair—‘Because this is the chair I was sitting in when I met you,’ he’d say.”

The book was in good shape according to Miller, but he wanted it as tight as possible. “It’s 700 pages, but every page is earned. You get completely lost in it.” The two talked through the entire book and finished in December 2018. “Our last conversation was a 10-hour phone call,” Miller says. “It was an emotional experience, and we both had the feeling of, ‘We did it!’ ”

“Wes was there every step of the way,” Chbosky remembers. “When he told me he reads Perks every year, I thought, ‘I have a partner for life.’ ”

Orion is the U.K. publisher, and foreign rights have sold in 19 territories to date. A seven-city tour is planned, as is a BookExpo appearance, where Grand Central will have one of those huge entryway banners promoting the book.

Chbosky tells me that a publishing house that lost the auction still had a request: “Will you please give us the other half of the book? We’re dying to know the ending!”