Two very different characters rewriting China's script By Stan Grant, CNN

Beijing (CNN) -- They are two men, separated by a gulf of power and privilege. One was born of the Chinese Communist Party, the son of a revolutionary hero and seemingly destined to shape China's destiny; the other has lived in the shadow of the state, poor, persecuted and blind.

Right now Chen Guangcheng, the activist, and Bo Xilai, the "princeling," are at the center of a storm that is prising open this secretive country in a way not seen for decades.

China's economy is slowing, the people are growing restless, and right at the time that the all-powerful Communist Party is preparing for a generational leadership change.

It is small wonder that some long-time China watchers, like author and former journalist James Macgregor, sense a new vulnerability in the middle kingdom.

"They're very nervous. I haven't seen China this nervous since post Tiananmen in 1990-91," Macgregor said.

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"They don't want a spark to go anywhere and they're pouring water on anything that could cause any problems."

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Chen spent more than four years in jail for charges arising from his campaign against alleged forced abortion and sterilization.

But since his release he's been locked down in his house in a small village under constant guard.

Now he is finally free after an extraordinary nighttime escape from his captors last week, and staring down China's leaders.

He released a video on the internet in which he makes allegations of brutality by state security. He accused his guards of violently assaulting him, his wife and elderly mother. He said they scoffed that they were untouchable and above the law.

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Chen also addressed China's Prime Minister Wen Jiabao directly and demanded hard answers.

"Premier Wen, all these illegal actions have baffled many people. Is it just local officials flagrantly violating the law or do they have the support of the central government?" He asked. "I hope you will give the public a clear answer."

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China's only answers so far have been an information black out and more arrests of dissidents.

State media is not running the Chen story, and Weibo, China's Twitter-like micro-blogging service, is being heavily censored with search terms blocked.

One of our producers has his account name banned, while key words like "blind," or "U.S. embassy" have been blocked.

But many Chinese people seem oblivious to the unfolding drama.

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CNN spoke to nearly 40 people on the streets of Beijing and could find only two people who even know -- or claimed to know -- who Chen is.

"It was on Weibo and some people are still re-posting. It went on circulating for a while before the topic started to get censored," one man said.

Yet in the rest of the world, Chen's plight is headline news.

According to his supporters he's now being sheltered at the U.S. embassy in Beijing.

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China and the U.S are saying nothing, publicly at least.

Privately, sources say there has been a flurry of back-door diplomacy to defuse a political time bomb that could rupture already brittle relations between the two powerhouses.

U.S. Secretary of State Hillary Clinton is in Beijing this week. She has championed Chen's case in the past.

Her visit raises critical questions: Will she demand his release? Will China accuse America of harboring a man it considers an enemy of the state?

Chen is not the only lit fuse in China.

One of the party's own, Bo Xilai, remains under house arrest.

The sacked chief of Chongqing, China's biggest metropolis, is under investigation for flouting party discipline. His wife is also suspected of murdering a close associate and British businessman, Neil Heywood.

Like Chen's case, the United States has also been dragged into the scandal surrounding Bo.

The former party chief's top policeman and right-hand man fled to a U.S. Consulate earlier this year, reportedly fearing for his life.

Diplomatic, business and political sources say Wang Lijun had fallen out with his boss after raising his suspicions that Bo's wife, Gu Kailai, was involved in killing Heywood.

Wang surrendered to Chinese authorities and has not been seen since.

Chinese insiders though say the Bo saga is not just about an alleged crime but a fight for the country's political soul.

Wang Kang knows Chongqing and has met Bo and his family. He told CNN Bo made enemies within the party after advocating a return to Mao-era revolution complete with slogans and inspired mass rallies to sing "red songs."

To Wang this has highlighted an emerging rift in the power structure. On one side: Bo and his other hard-line supporters, and on the other: pro-reformers.

The current investigation, suggests Wang, needs to be seen as part of a broader ideological battle.

"Bo's case is very delicate for the central government to handle," he said.

"The focus cannot be limited to discipline violation, corruption and murder, although severe enough. It must be much wider or Bo and his supporters won't fully yield."

China has been exposed by the plight of two men from very different worlds in the same fractured country -- Chen, a self-taught lawyer who has used his voice for the poor and powerless, and Bo, the ambitious but ruthless princeling.

Together their stories encapsulate what critics see as the worst of China, a country where the poor have no protection from the law, where persecution is common, censorship and corruption rampant, and where power and wealth is too often inherited, not earned.

Yet if Chen and Bo are defined by the system, what happens to them could redefine that very system itself.

The Communist Party is turning on one of its own at a time when a lone, long-silenced voice is asking the party what it stands for. The answer won't just decide Chen's future but maybe the future of the country.