In 1993, every parent’s nightmare became a reality for Ron Suskind and his wife, Cornelia, when their 3-year-old son vanished. But the Suskinds’ youngest child had disappeared right in front of them.

One day Owen was a rambunctious toddler with a ready smile and a budding vocabulary. The next day he was withdrawn, bereft of words, inconsolable. After a stream of doctor visits, Owen was diagnosed with regressive autism, a developmental disorder that typically appears between a child’s first and third years.

The condition turned Owen inward and upended the way he engaged with the world, including his parents and brother. Suskind’s new book, “Life, Animated: A Story of Sidekicks, Heroes, and Autism,” is an affecting account of how the family gradually reconnected — through Disney movies.

‘A world was growing inside of him, in that silent place.’

“It was always a question we asked: What is it about his affinity with Disney?” Suskind, a Pulitzer Prize-winning journalist and currently a fellow at the Safra Center for Ethics, said in a recent interview. “We felt our way along here for almost two decades. We know a lot now through this kind of search and find that we discover along the way. Mostly, we just said, ‘There’s something about these films that speaks to him.’”

The first insight came about a year after Owen’s diagnosis. As he watched “The Little Mermaid,” Owen wasn’t simply babbling, his father realized — he was repeating part of a song lyric from the film.

“That’s was the beginning of the process of starting to see the movies as he sees them,” said Suskind. “That was the key.”

Owen had always been a fan of the films, but at the onset of autism, his interest in grew into an obsession, Suskind said. He would watch and rewatch the movies scores of times. When he was 6½, his parents came to understand that the activity signaled far more than the compulsive behavior of an autistic child. They realized, in one astonishing moment, that their son was using the Disney canon to navigate the world.

“Owen says: ‘Walter doesn’t want to grow up, like Mowgli or Peter Pan,’” Suskind recalled. He was describing his older son’s ninth birthday in 1997, and his younger son’s comment, seemingly out of nowhere, after seeing his brother in tears as the party wound down.

“That was a huge moment for us. That was complex interpretation, speech. He had never done that before. … He had been largely silent for so many years, and he then said something that startling. It gave us a glimpse into what was happening inside — that a world was growing inside of him, in that silent place.”

With help from specialists, the Suskinds learned in time to negotiate Owen’s private domain. By day they followed their regular routines, but at night the family would inhabit an undersea world, an enchanted castle, or a lush jungle, connecting through a musical crab, a French candlestick, or a benevolent bear.

“The more we gently moved into his world and brought fun to it, playing the characters, the more he said, ‘Come on in.’”

Role-playing was key. Suskind would recite lines from, say, “Aladdin,” and his previously withdrawn son would become voluble, quoting at length from the film. But it wasn’t merely echoing Owen was engaged in — he was enriching his emotional life. Disney, it turns out, was an ethical and social education. In addition, writes Suskind in “Life, Animated”: “We discovered that he learned to read using the slowly scrolling credits at the ends of movies.”

Suskind discussed his most personal work on a cloudy afternoon in a small fifth-floor office at the edge of Harvard Square. A recent flurry of book-related interviews and speaking engagements hadn’t quelled his energy. He was quick to laugh, and offered dead-on impressions of Sebastian, the Jamaican crab from “The Little Mermaid,” and Merlin from “The Sword in the Stone” — voices that have so often brought him closer to his son.

In 1995, Suskind won the Pulitzer Prize for feature writing for articles profiling high school honors students in Washington, D.C. His 1998 book, “A Hope in the Unseen,” was based on those pieces. His more recent works, which he called “big, noisy books,” have explored aspects of presidential power.

Suskind sees a common thread running through much of his writing.

“In some ways, I searched the whole world for almost 30 years for people who are left behind, and it dawned on us … that the most dramatically left-behind person that I had met, by this twist of neurology, was living in the bedroom.”

When Owen was about 11, Suskind saw him feverishly copying images of Disney characters in a sketchbook — images of sidekicks, those characters who in Owen’s words “help the hero fulfill his destiny.” Scrawled on the last two pages of the notebook were the lines “I am the Protekcter of Sidekicks” and “No Sidekick Gets Left Behind.”

“He is responding to us and the wider world he is now beginning to see,” Suskind writes. “Other kids are racing forward, with their dreams of heroism. He’s caught in the starting blocks, a sidekick. And he becomes protector of the sidekicks, the supporting cast, demanding that none of them be left behind. That’s all. Not asking for the world, here — just don’t leave us behind.”

Deconstructing the films’ hold on his son, Suskind pointed to the genius of Walt Disney, a businessman with no shortage of creative flair, who thought that moving cartoons should be works of art and “carry all of the real emotions, the big ones.”

Affinity therapy, Suskind noted, runs counter to much expert advice over the years. Instead of trying to curb a passion for things like trains, or maps, or the films of Walt Disney, as some specialists have advised, it’s possible, with a careful approach, to exploit those interests and tap into something deeper.

“Once you get into the affinity what you will find in that underground cavern is that there are things to work with, there are tools, there’s maps, there’s navigational equipment … [and they] will help you, because they will want to tell you this is the thing that they love. And they want to connect.”

Disney has helped to enhance Owen’s speech, his social appropriateness, his contact with others, said Suskind. “Then he was able to build a vehicle, with us, that he eventually drove out into the world of sunlight and human interactions, which is where he has lived for many of the past — certainly the past few — years.”

The book, excerpted last month in The New York Times Magazine, has already struck a chord. One young woman, struggling with post-traumatic stress disorder, wrote to tell Suskind she pasted the words “Remember Owen” on her wall.

The research community also taken note. “Scientists have been calling by the minute,” said Suskind.

And the author has been reaching out himself, speaking at MIT’s Simons Center for the Social Brain and, as part of World Autism Awareness Day, the U.N. Later this month, he will give a speech at the National Institute of Mental Health.

Owen, living at a residential school on Cape Cod, has started a Disney Club with several other students, many of whom have “modest expressive speech.” The students watch a film and then pause to discuss how they relate to aspects of the plot and characters. Suskind, an occasional guest, recalled an encounter with a young club member who “doesn’t speak very often.”

“He says, ‘You know Pinocchio’s my guy, because I feel like a wooden boy, and I’ve always dreamed of feeling what real boys feel, and I was born with wooden eyes, and it’s so hard to see out of them.’

“That kind of expression coming out of a teenager …” Suskind said, shaking his head. “That is a very powerful message of an inversion of assumptions, a recasting of yardsticks that we use to measure worth. And that is, I think, progress.”