Somewhere in Hollywood a scriptwriter must be firing up a laptop to tell the story of the blind Chinese dissident Chen Guangcheng.

But it won’t have a Hollywood ending. This story can only end badly, with humiliation for Secretary of State Hillary ClintonHillary Diane Rodham ClintonKoch-backed group launches six-figure ad buy against Heitkamp Trump keeps up 'low IQ' attack on Maxine Waters GOP leaders to Trump: Leave Mueller alone MORE and probably exile for the human-rights activist who originally wanted to stay in China and study under an agreement negotiated with the Chinese authorities since he fled house arrest and pitched up at the U.S. embassy in Beijing.

When the Twittersphere erupted yesterday with criticism of Clinton over the administration’s naivety in trusting China to abide by the deal, I thought that surely the secretary of State would not have spoken publicly about the arrangement unless she had obtained cast-iron guarantees. It turns out that she did not, and that the Chinese had lured Chen out of the safety of the U.S. embassy by playing the oldest trick in the communist playbook: family blackmail.

Now reunited with his family in a Beijing hospital but fearing for their safety, Chen wants to leave the country. The American diplomats involved in the negotiations with the Chinese have acted in the interests of Chen from the start, according to briefings by the U.S. side. They must now be scrambling to find a way for him to leave — he says he wants to fly out on Clinton’s plane on Saturday. But the U.S. leverage is limited.

For a brief moment yesterday, it seemed that the Chinese were prepared to review their longstanding policy and allow a high-profile critic (of forced abortions) to remain in the country with impunity. It was naïve of the Americans to believe that such a U-turn was possible, and that China would abide by the deal that promised to reunite Chen with his family and allow him to study law at the university of his choice. But Chen was also naïve: Did he seriously believe that he would be able to speak with Prime Minister Wen Jiabao?

In China, political dissent remains a one-way street, as the Tiananmen square protesters know only too well, and inevitably leads to a lonely exile in America. Chen is about to find that out the hard way.