This is a tale of intrigue, betrayal, courage and horror that started when a group of students in Beijing set up the the New Youth Study Group to debate political reform in China. They made a dreadful mistake, however, inviting a student to join them, not knowing he was a spy with the Gestapo Ministry of State Security. The story ended with three of them sentenced to lengthy prison terms.

If you don’t know the story, you have to take a look at this detailed and wrenching article. Among its observations:

Nearly 15 years after the Tiananmen Square massacre and 13 since the fall of the Soviet Union, the Chinese Communist Party is engaged in the largest and perhaps most successful experiment in authoritarianism in the world. What happened to the New Youth Study Group offers a glimpse into the methods the party uses to maintain its monopoly on power and the difficult moral choices faced by those caught in its grip.

The fate of the study group also illustrates the thoroughness with which the party applies one of its most basic rules of survival: Consider any independent organization a potential threat and crush it.

The eight members of the New Youth Study Group never agreed on a political platform and had no real source of funds. They never set up branches in other cities or recruited any other members. They never even managed to hold another meeting with full attendance; someone was always too busy.

And yet they attracted the attention of China’s two main security ministries. Reports about their activities reached officials at the highest levels of the party, including Luo Gan, the Politburo member responsible for internal security. Even the president then, Jiang Zemin, referred to the investigation as one of the most important in the nation, according to people who have seen an internal memo summarizing the comments of senior officials about the case.

The leadership’s interest in such a ragtag group reflects a deep insecurity about its grip on power. The party has delivered two decades of rapid growth, defying those who believe economic reform must lead to political liberalization. But it is struggling to manage rising social tension and popular discontent and remains especially wary of student activism, which sparked the 1989 pro-democracy demonstrations in Tiananmen Square.

Five months ago, their appeal was rejected and they languish in prison today. The story of how they were betrayed and arrested is gripping and disturbing, as are the musings of their betrayer, whose nonchalance about the whole thing is terrifying. I hope it’s at least of some consolation to them, as they serve their 8- and 10-year jail terms, to know that things are getting better, and the country’s reforming.