Photograph by Ed Kashi VII

It’s an understatement to say December was a big month for writer Suki Kim. Just after appearing on The Daily Show with Jon Stewart—a coup for any author—her new book, Without You There is No Us: My Time with the Sons of North Korea’s Elite (Crown, 2014), hit The New York Times bestseller list for e-book nonfiction, and print copies were scarce. “Sorry readers,” Kim posted on Twitter minutes before our interview. “Hardback temporarily sold out @Amazon, being restocked; Available @ B&N.”

The book is a memoir of Kim’s six months undercover in North Korea, while teaching English at Pyongyang University of Science and Technology, a private university funded and operated by Western missionaries to educate 270 sons from the country’s elite families.

After taking several highly supervised visits to North Korea over the past decade as a journalist Kim says, “I knew I had to live there to tell this story. All Americans were hearing about North Korea were crass Kim Jong-il jokes or about the famine there,” she says. “But there are 25 million people being held hostage in the nation, not allowed to move to the next town, not allowed to think freely.”

With a recommendation from a friend of the university’s president, Kim’s application was approved quickly, although she did not hide the fact she was a writer. Kim says through embedding in the school in 2011, she could tell the stories of individual North Koreans, to make them more real to Westerners, “similar to the way people read the stories of the 9/11 terror victims and felt they could have been your friend or my friend.”

In the book, Kim details the daily lives of the young men—“the crème de la crème, the future leaders of North Korea.” Kim chronicles how students were heavily guarded, “never had a single minute alone,” and were not allowed to leave the campus, where speakers constantly blasted music praising the Great Leader—Kim Jong-il at the time. “The system is all about paranoia and distrust,” she says. “They weren’t allowed to call their parents, but they would lie [to me] and say they did, to protect the system.” Kim tells how these students “at the MIT of North Korea” didn’t even know the Internet existed, and teachers were forbidden from speaking of it. She says the students were sheltered for their age. “These lovely 19-year-olds, they felt like my children,” she says. “But it was heartbreaking, unbearable to see these children in this Stalin-like system.” She blurred their identities in the book, “so no one could be singled out. But mostly they come across as incredibly loyal to their Great Leader.”

Kim says she has been obsessed with North Korea since she was a child growing up in 1970s South Korea, where her grandmother and aunt longed for the children from whom they had been cruelly separated when the country was divided by the Allies after World War II. Kim herself was traumatically separated from her motherland at age 13, when the South Korean economy stumbled and her wealthy family “lost everything overnight.” Her parents, along with Kim and her two siblings, moved to Queens. The teen, who had grown up with maids and governesses, was suddenly poor and labeled Asian. “Race was abstract to me, being a person of color was something I’d never thought about. My identity of who I was disappeared overnight,” she says. “I spent my teenage years mute, because I didn’t speak English.”

“The theme of separation is something I am haunted by,” she says. “I don’t know where home is. In a way, I’m trying to find that in my books.” Kim’s first book, The Interpreter, is a novel centered on New York City’s Korean community.

Just as Kim’s current book hit the bestseller list, the news broke that Sony Pictures Entertainment was limiting its scheduled Christmas Day theatre release of the Seth Rogan film The Interview, due to terror threats. In the political satire, the CIA recruits two journalists to assassinate North Korean dictator Kim Jong-un.

Based on her unique access to North Korea, Kim was bombarded with interview requests from a host of major media outlets, including CNN, MSNBC, and National Public Radio. Kim says the comedy, which was eventually released online and in a small number of theatres, is no joking matter. “It’s cringeworthy,” she says. “If Sony can’t make a comedy about 9/11 or Ferguson, why make a movie about a country where 25 million human beings are hostage.”

As for her own experience, Kim told Jon Stewart, “I wanted so much to tell [my students] about the world, but if I did, it could be dangerous for them.”

“And for you,” said Stewart.

“If I would have got caught I would have been called a spy,” Kim said. “Which I guess I was.”