adapted from gu long's classic novel xiao li's flying knife series "the passionate swordsman" bbb。 during the ming dynasty, li xunhuan (played by jiao enjun), a civil and military genius, was famous in the world with his flying sword skills. he wanted to live with his cousin lin shiyin (played by xiao qiang) and retired from the world, but he was helplessly surrounded and intercepted by the so-called righteous people. by chance, li xunhuan entrusted lin shiyin to his sworn brother long xiaoyun (played by lin liyang), pretending to marry a prostitute xianer (played by zheng jiaxin). from then on, the couple separated from each other. lin shiyin and long xiaoyun became their biological son long xiaoyun (played by zhang chen), and li xunhuan began a new career in the world. after separation, li xunhuan and the granddaughter of the old man tianji, sun xiaohong (played by alyssa chia), the unknown swordsman a fei (played by wu jing), became siblings. forced by the hard work of enemies and the secret framed by long xiaoyun and his son, li xunhuan was involved in rounds of entanglements, and has always been obsessed with lin shiyin and li xunhuan. at the same time, the appearance of the jinghong fairy yang yan (played by yu feihong) has rewritten his ill-fated fate.