After hundreds, perhaps thousands, of years of disciplined training in Taoism whilst living in a cave on Mount Emei, the protagonist Bai Su Zhen (Pure White Silk) has, with the help of a heavenly immortality pill, transformed herself from her true original form as a snake into a human form to seek immortality in the human world in her quest for divinity, guided by the Mother of Mercy, Guan Yin (lit. "Watcher of the World's Cry")
She then meets and masters in single combat her would be ravisher. He then transforms himself into a female form and becomes her aide de camp. He is known as Xiao Qing ("Small Green") and like Bai had originally been a serpent.
Bai at some point had been saved from being killed for her snake gall by a young cow-herd known to her only as her benefactor. One of her reasons to enter the human world was to repay him. Guan Yin had told him he would meet a higher man on Tomb Sweeping Day at the West Lake. Whether higher was meant literally or metaphorically was uncertain. Bai and Xiao Qing together search for this benefactor, Xu Xian. Bai finds him and it is love at first sight. They meet on the Broken Bridge on Tomb Sweeping Day. Hanwen is there to visit the grave of his deceased parents. In this life Hanwen works in a pharmacy and studies medicine. Because Hanwen had saved Bai in her previous life when she was a snake she wishes to repay him. The two fall in love, marry, have a child, and are pursued all along the way by a religious zealot, Fa Hai. Fa Hai believes that a demon is always a demon and can never become good and belongs not in the human world hence his dogged pursuit. Bai has a child with Hanwen after their marriage. To save that child she agrees to be imprisoned in Lei Feng Pagoda (which literally means thundering wind tower), a symbol of the tomb.
