Adapted from Gu Long's classic novel "The Sentimental Swordsman" in the Xiao Li Flying Dagger series. During the Ming Dynasty, Li Xunhuan (played by Jiao Enjun), a versatile man of both literary and martial arts, became famous for his flying knife skills. He wanted to live with his cousin Lin Shiyin (played by Xiao Qiang) and retire from the underworld, but he was chased and intercepted by the so-called righteous people. By mistake, Li Xunhuan entrusted Lin Shiyin to his sworn brother Long Xiaoyun (played by Lin Liyang), and pretended to marry the prostitute Xian'er (played by Zheng Jiaxin). From then on, the couple separated, Lin Shiyin married Long Xiaoyun and gave birth to a son, Long Xiaoyun (played by Zhang Chen), and Li Xunhuan began a new life in the underworld. After the separation, Li Xunhuan became brothers and sisters with Tianji's granddaughter Sun Xiaohong (played by Alyssa Chia) and the nameless swordsman A Fei (played by Wu Jing). Under the pressure of his enemies and the secret frame-up of Long Xiaoyun and his son, Li Xunhuan was involved in one round of entanglements after another. He could not forget Lin Shiyin. At the same time, the appearance of the fairy Yang Yan (played by Yu Feihong) changed his ill-fated fate.