Yang Naiwu and Xiao Baicai are one of the four major mysteries in the late Qing Dynasty.

During the Tongzhi period, Yang Naiwu and Ge Bishi were suspected of committing adultery and murdering their husbands. After being tortured, they confessed and were put on death row. The case alarmed the court. Although they were cleared after several more trials, the tragic experience of the two people being tortured is still lamentable. The character Yang Naiwu, also known as Shuxun and Zizhao, was clarified by Yuhang Town, Yuhang County, Zhejiang Province. A native of the alley, his family's business is planting mulberry and raising silkworms. He has an upright character. He was a candidate for the Guiyou Ke Township Examination and is known as "Mr. Yang Er". He married three wives, namely Wu (first wife, died early), Dayang Zhan (died in childbirth), Xiao Yang Zhan (real name Zhan Caifeng).

Ge Bi’s name is Bi Xiugu, nicknamed Xiao Baicai, the adopted daughter-in-law of the Ge family. She is fair and beautiful; because she wears white clothes and green trousers, she is known as "Xiao Baicai". Yang Naiwu taught Bi Xiugu how to read, and the two became close friends, so there was a rumor in the neighborhood that "sheep eats cabbage." After Gebishi's husband Ge Pinlian suffered from fire syndrome. On the seventh day of October in the twelfth year of Tongzhi (1873), Ge Pinlian's old illness relapsed. On the ninth day of October in the twelfth year of Tongzhi, Ge Pinlian died suddenly. The autopsy concluded that he was poisoned by arsenic.