Blind activist Chen Guangcheng's startling escape triggered a new diplomatic crisis for Beijing and Washington. But he's only the most recent in a series of rescues and disappearing acts by resourceful (and desperate) Chinese dissidents. Hundreds of human-rights advocates and protest organizers found their way to freedom via a sophisticated and well-funded "underground railroad" known as Operation Yellowbird after the 1989 crackdown on Tiananmen protesters. And more recently a smaller number have defied the government's high-tech surveillance techniques to escape, or attempt to. Some key cases:
