One evening in November 1977, in the port city of Niigata on Japan's northwest coast, 13-year-old Megumi Yokota walked home from badminton practice, said goodnight to two friends, and disappeared.

Twenty years later, an activist gave a lecture in Niigata and relayed a rumor about a 13-year-old girl, carrying a badminton racquet, who was taken from the city. He'd heard the tale just a short time earlier from a Japanese reporter, who got it from a South Korean intelligence officer, who had heard it from a North Korean defector.

After the lecture, writes Robert Boynton in his new book, "The Invitation-Only Zone: The True Story of North Korea's Abduction Project," an older man approached the activist and said, "That girl with the badminton racquet. That just has to be Megumi Yokota."

That was the moment when Japan began to recognize a horror: For years, North Korean spies had been kidnapping people off their streets, at least a dozen and perhaps more. Once in North Korea, the abductees were sequestered for indoctrination in North Korea's perverse view of the world. Then, they were given homes in rural, fenced compounds known to North Koreans as "Invitation-Only Zones."

North Korea also kidnapped people from other parts of Asia, the Middle East and even Europe. By many estimates, most abductees came from South Korea, sometimes snatched off boats within swimming distance of shore. Many were well cared for and lived better than North Koreans, particularly when famine hit the country in the 1990s.

Boynton spends part of the book trying to figure out why North Korea did it. Without help from North Koreans, he doesn't land on a single reason. One explanation that emerged from several of the released abductees, and at one point from the very top in Pyongyang, is that North Korea wanted them to raise foreign-looking children who could be trained as spies.

It took the Japanese government until 2002 to get North Korea to acknowledge what it had done. And when North Korea did, it said only five were still alive, a number no one in Japan believes and that remains an issue between the two countries today.

As compelling and tragic as the abduction stories are, "The Invitation-Only Zone" is not simply another book about North Korean barbarity. Boynton connects the abduction project to the evolution of the relationship between Japan and both Koreas, digging into the pain the peninsula experienced as a colony of Japan for nearly four decades until the end of World War II.

The concept of race, introduced to Japan by Americans in the 19th century, became the justification for Japan's conquest of Korea and other parts of Asia in the early 20th century.

Although rid of the Japanese after the war, Koreans in both the North and South clung to the lessons of racial purity the Japanese taught them. A few decades later, the North Korean regime took race-based nationalism to a new extreme, leading to, as dictator Kim Jong Il told the Japanese prime minister in 2002, "regrettable conduct."

Evan Ramstad, the Star Tribune's digital business editor, was Korea correspondent for the Wall Street Journal from 2006 to 2013.