"A Cold Blade Startled the Hero: A Record of Mysterious Cases in Jianghu" tells the story of Shen Yan, the former young minister of Dali Temple who was wrongfully demoted and then got involved in the Jianghu due to a "painted skin ghost" case in Luoxia Town, Jiangnan. He teamed up with Su Wan, the daughter of a drugstore who knew toxicology, and found clues to the "Xuanwumen Secret Letter Theft Case" twenty years ago from the gold powder under the fingernails of the dead woman's corpse and the strange handwriting in the embroidery.
During the investigation, they encountered the bone-transformation mystery of the "Bone-eating Station", the revenge of the "Puppet Grave", and were involved in a series of mysterious cases such as the "Moxiang Murder" and the "Shadow Puppet Festival" in the capital. Xiao Lin, a knight-errant, is both good and evil. Sometimes they are enemies and sometimes they join forces. The three of them discover that each case points to the secret letter - the late emperor's edict that can subvert the court.
In the end, the three of them broke into the main altar of Broken Soul Valley and pieced together the complete secret letter between the mechanism and the bones. They not only revealed the truth about the Heavenly Official Zhao Chong's murder of his brother to seize the throne and framed Shen Yan's father, but also outsmarted the situation in the final showdown. After the injustice was over, Shen Yan refused to return to the court and returned to Luoxia Town with Su Wan. However, while sharpening his sword, he received a letter from Xiao Lin - the murders in the world were not over yet, and a new investigation was in sight.
