The difficulty of charitable organizations overseeing brokers has created problems. Four sources on the Underground Railroad say that since 2017, disputes between refugees and brokers have risen. Male brokers have been known to rape female refugees. Scams to bilk North Koreans out of their resettlement funds are common. Several sources on the Underground Railroad, however, pointed out that without brokers, no rescue can be successful.

Ultimately, the bootstrapped nature of the Underground Railroad—which has been justly celebrated in its creation—has also limited its effectiveness in the long run. Few rescue organizations seem to know what their peers are doing, and each has a separate handshake agreement with brokers. Few NGOs follow up with refugees once they reach South Korea. Though most organizations insist that they exercise oversight of brokers, that control seems limited in practice, and the brokers themselves said they were able to act with impunity. Rules or even just clearer expectations between brokers and charitable organizations might help to avoid conflicts. “If we had government support to do this legally, many of these problems would vanish,” said one broker. And the goals of the two groups are not so dissimilar that they can't find a mutually advantageous solution. Two brokers described being attracted to the work for similar reasons as activists, though they acknowledged they also needed to make a basic living. “I feel like I'm saving individuals from hell,” said one. Activists and brokers agreed that the brokers weren't getting rich off the work, earning only a few hundred dollars for each rescue.

As I left Seoul early this year, I was uncertain whether Kim had misused any of NGI's funds. But in the lawless Underground Railroad, what was justified to save lives often depended on who was making the call. “I have seen the sacrifices Kim has made for 20 years,” said Youngja Kim, who explained that NKHR had found no financial improprieties with Kim and would continue working with him.

On the other hand, NGI is now employing new brokers. “We could no longer trust Stephen after he was not clear with us in the beginning about where the money went,” said Bae, who was never satisfied with Kim's accounting of NGI's funds. Bae added, “We feel that it is not fair to ask North Korean refugees to pay for their own escapes.” Bae was working to make sure that the refugees who had paid brokers were being reimbursed.

When Faith was contacted for a final round of fact-checking, about a month after making her original accusations, her anger against Kim had softened, and she now believed that he had probably used the disputed money for his ministry, not for himself. “I think it was all done with good intentions,” she said, “but his way could be misleading to others.” Ultimately, the mystery that shrouds the Underground Railroad makes it difficult for even the people in it to tell what happened, let alone an outsider like me. The best I could do was to report everyone's story and let the world judge what had occurred.

The last time I met Stephen Kim, in a café in Seoul, his exhausted face betrayed the toll that the scandal had taken on him. The mythic aura, the mysterious smile, had vanished. There was much that I would never know about him, but he seemed freshly human to me now: a man both heroic and flawed.

In the end, the times that I most doubted Kim was when he had tried to build up the myth of “Superman.” The tragedy, of course, was that his story didn't need embellishment. In fact, everything that he had achieved was all the more incredible for the fact that he is an ordinary man. It was the human imperfection of all the activists I met that helped make what they achieved so extraordinary. For what mattered most, at the end of the line, was that Faith and thousands of other North Koreans were now on the right side of freedom.

In early 2019, Faith bused to the demilitarized zone, the heavily guarded no-man's-land that divides the two Koreas, just 35 miles north of Seoul. As foreigners and South Koreans gawked and snapped photos from a tourist overlook, she stared at the low mountains of North Korea. She could not help thinking about the family she had left behind there, though she had little chance of ever seeing them again. Unless they, too, escaped through the Underground Railroad.

Doug Bock Clark's last story for GQ, “American Hostage: The Untold Story of Otto Warmbier,” appeared in the August 2018 issue. His first book, The Last Whalers, was published in January 2019. This article was completed with support from the Pulitzer Center on Crisis Reporting.

A version of this story originally appeared in the April 2019 issue.