July 27, 2012 -- There is perhaps no more glorious moment for a country than when it hosts the Olympic Games.
Nations plan their opening ceremonies for years, calling on their top talent to weave a story of national unity and strength. But with glory comes scrutiny, and sometimes something happens to rip a hole in the carefully crafted tale.
That's what happened four years ago in Beijing.
The Bird's Nest stadium, a soaring feat of architecture, was the centerpiece of those games. But ironically, it would help expose the dark side of China's stubbornly authoritarian regime.
Ai Weiwei, an artist known as China's Andy Warhol, helped design the Bird's Nest. Then he did a surprising thing: He walked away and boycotted the Beijing Olympics, accusing the Chinese government of using the games as propaganda.
It wasn't the first time Weiwei flew in the face of authority on behalf of freedom of expression. Since the 2008 Olympic Games, he has become one of China's most politically outspoken critics. He has been beaten, prosecuted and even held in secret detention for his efforts to expose his homeland's oppression of its people.
The man China wants silenced spoke exclusively with "Nightline" at his studio and home located in a Beijing art district, where he said he fears there will be a knock at the door at "any moment." Weiwei speaks fluent English and once lived in the United States, but he is remarkably soft-spoken.
Today, the artist lives under constant surveillance. Cameras, put in place by Chinese authorities, line the street outside of his studio. He said there are 15 cameras on his street, tracking his every move.
"Of course we are watched," he said. "My phone is tapped. They know you are here."
Weiwei's Twitter feed is blocked in China, but like many others, he gets around the so-called firewall and is a prolific teeeter. It is his weapon of choice against the Chinese government. Before 2005, the artist said he had never touched a computer keyboard, and now there may be no other dissident who has used Twitter more effectively.
"I thought it was a miracle," he said.
It was the earthquake in China's Sichuan province in 2008 that spurred Weiwei into action. More than 68,000 people were killed, many of them children whose shoddily built schools collapsed around them. The government refused for months to release a death toll of the names of those killed.
In 2009, while in the western city of Chengdu to testify at the trial of a fellow activist, Weiwei said Chinese police visited him at 3 a.m. in his hotel room. His own camera recorded them punching him in the head. As he was escorted out of his hotel room, he tweeted out a self portrait. It went viral in seconds.
"The only way to do it, to win the battle, is to let the world know what is happening," he said.
In a new documentary about Weiwei's life called "Never Sorry," director Alison Klayman seeks to show how this artist became an enemy of the state. Klayman followed him for three years.
"I don't think he was ever safe then, and I don't think he is safe now," Klayman said.
The confrontation between Weiwei and the Chinese government reached a tipping point in April 2011, when he was taken into secret detention by authorities. There was an international outcry for his release, but the government accused him of pornography and tax evasion. They held him for 81 days.
More than a year after he has returned home, Weiwei said the experience is still hard to talk about.
"You have no lawyer, you cannot contact your family, you don't know where you are," he said. "You believe you are very stupid to go against this. You believe your story will never be heard."
But it was. Thousands of Chinese fans donated more than $1 million towards his $2.4 million tax fine.
After his release, Weiwei returned to Twitter and to his art studio. His biggest incentive for staying out of trouble, he said, is the 3-year-old son he adores, but Weiwei said he won't stop his fight.
"I don't think they can win…I never think they can win, not for a second," he said. "I think people's desire for liberty, for happiness, for freedom, nobody can stop it. We are human."