In Yingtian Mansion during the Yongle period, the silk merchant Wang Yuanbao died mysteriously in a secret room. The circumstances of his death were exactly the same as the "Xiu Chun Knife Murder Case" three years ago. Jin Yiwei Shen Yanqing, who was ordered to investigate the case, bumped into Su Qingqing, who claimed to be a "folk Sherlock Holmes" at the crime scene. One is the iron-blooded Tiqi who believes in "evidence does not lie", and the other is a clever girl who is good at "people's hearts are clues". The two are forced to team up to investigate the case. As the investigation deepened, they discovered that the half piece of mandarin duck embroidery held in the deceased's hand was inextricably linked to the missing treasure of Emperor Jianwen and the secrets of the harem. When more victims died in the same way, Shen Yanqing's embroidered spring knife began to point at his own people, and Su Qingqing's secret hidden in the hairpin was about to set off a bigger storm.
