Xiao-Bai, a white snake demon, is on a mission to assassinate the Emperor's Taoist advisor, who is killing snakes to attain immortality and gain the Emperor's favor. However, she is ambushed by the advisor's followers and defeated. Luckily, a demonic hairpin from the Snake Mother saves her life, but at the cost of losing her memories. Xiao-Bai awakens in a Snake-catcher village, unaware of her true identity as a demon, and surrounded by her enemies. She meets Xu Xuan, the man who saved her, and they develop a romantic bond while embarking on a quest to uncover her past and the secrets of her hairpin. Their journey is thwarted by Xiao-Qing, Xiao-Bai's sister, who pledged to retrieve her within three days or die trying. As Taoists, humans, and demons converge, a tale of forbidden love unfolds.