How “The Accusation” came to light is a story of its own. In 2012, Mr. Do received an urgent call from fellow human rights activists in China: A North Korean woman had been caught by the Chinese police and was about to be extradited to the North, where she would certainly face time in a prison camp. Mr. Do raised cash to help her bribe her way out and to bring her to South Korea.

She told Mr. Do that before fleeing the North, she went to say goodbye to a relative, Bandi. He asked her to take a seditious manuscript he had been hiding, but she was too afraid to smuggle it across the border into China; if she was caught, she, the writer and their families would certainly have been banished into prison camps, if not executed.

She gave Bandi’s real name and his North Korean address to Mr. Do, who hired an ethnic Korean in China to travel to North Korea as a tourist and discreetly contact the writer. In 2013, the manuscript was smuggled out, hidden among works of propaganda glorifying Kim Il-sung, the country’s founding president and grandfather of the current leader, Kim Jong-un.

Mr. Do was a well-known advocate for human rights in North Korea and a member of the South Korean government’s National Unification Advisory Council. But when he offered the manuscript to publishing houses in South Korea, most declined, as Bandi’s existence in North Korea has never been independently verified. All they had to rely on was Mr. Do’s word.

Mr. Do faced an agonizing predicament. He wanted to provide as much information as he could to establish that the book was not a hoax. But he also had to protect Bandi’s identity to keep him safe from retaliation by the North Korean regime. This is about all Dr. Do will say about Bandi’s identity: He was born in 1950. He has belonged to the Korean Writers’ Alliance, a government-controlled organ dedicated to producing censored literature for state-run periodicals of the North.   

“The Accusation” was published in South Korea in 2014 by Chogabje.com, a conservative news website and publisher, but failed to gain much attention. Mr. Do persisted, pitching the manuscript to publishers abroad. A breakthrough came when a French translation was released last year. Other translations quickly followed.

Mr. Do said that the last time middlemen checked on Bandi, nine months ago, he was safe and was aware of his book’s publication in the outside world. A regular guest on a South Korean radio program broadcast into the North, Mr. Do has been providing updates on the book, hoping that Bandi will hear him. “The Accusation” has earned $10,000 in royalties. Any profit will be used to support Bandi’s family and books by defector writers living in South Korea, Mr. Do said in an interview.

Only a handful of people have been allowed to examine the original manuscript. Mr. Do recently let a reporter for The New York Times check it, but did not allow it to be photographed, fearful that the North Korean regime might be able to identify Bandi by scrutinizing his handwriting.

As an additional protection, Mr. Do said that he altered the names of the characters and locations in the stories. “I assumed that they were fictional in the first place,” he said. “But I did not want to take chances. The more he is known, the more I am worried about his safety.”

Kim Joeng-ae, a former North Korean propagandist now in Seoul, is a member of North Korean Writers in Exile PEN Center, a branch of PEN International, the literary and human rights organization. She said that she and other writer defectors had studied Bandi’s stories and concluded that they were indeed written by a North Korean.

There are expressions in his book that only a North Korean would be able to write, she said. (The version published in South Korea has footnotes to guide readers though words only used in the North.) His stories also closely followed the “seed theory,” a guideline of all North Korean writers, which requires them to structure their writing tightly around a core ideology — though Bandi uses the same device to attack the party line.

Bandi was the pen name the writer chose for himself, Mr. Do said. In one of 50 poems smuggled out with the manuscript of “The Accusation” and to be published separately, Bandi explained his alias. Bandi, he wrote in a poem, was “fated to shine only in a world of darkness.”

In the book, North Korea is a country where a woman is programmed to show grief over Kim Il-sung’s death with flowers, streaming tears and a heart-rending cry of “Great Leader, Father!” — even as her husband is languishing at a political prisoners’ camp.

In one story, “So Near, Yet So Far,” a son is unable to see his dying mother because he lacks the requisite travel permit. He compares himself to “a dragonfly stuck in a spider web.”

“Ultimately, this is a textbook on the human rights condition in North Korea,” Mr. Do said. “What it does is to show that in North Korea, ordinary life itself is slavery.”