Jianggao: Capital of Seven Days

On the last seven days of September 2006, Zhang Jianguo, a boilermaker at a textile factory, started from a piece of paper and went 17 meters underground in the third workshop. Eleven fake work-related injury agreements, twelve liquid nitrogen containers, and a death tunnel extending at the bottom of the Qingjiang River—it took him seven days to walk through the entire tunnel, seal all the evidence into four letters, and then collapse in the duty room. There was only one sentence in the letter: Find those eleven people and say sorry to their families. Twelve years later, his son Zhang Zhengdong opened one of the letters.