During the Xuande period of the Ming Dynasty, Shen Yan from Fusi Xiaoqi, Jinyiweibei Town, was sent to Qingxi Town to investigate the case of a "shadow puppet murder case". This case is very strange - the deceased all held strange shadow puppets in their hands, and the appearance of death was exactly the same as that of the shadow puppets. They had also seen "moving shadow puppets" before they died. Shen Yan thought it was just Jianghu magic at work, but he didn't expect that while investigating the case, he bumped into a girl Su Qingqing wearing a rouge-colored skirt and carrying a calculation box on her back.
Su Qingqing is a descendant of a branch of the Qintian Prison. She is proficient in arithmetic and mechanical skills. She came to Qingxi Town to track down the missing arithmetic teacher, but she accidentally got involved in the shadow puppet case. One is the "Rough Man Jinyiwei" who relies on swords and shadows to investigate cases, and the other is the "witty little money fan" who relies on calculation and deduction to solve mysteries. The two of them disliked each other (Shen Yan thought Su Qingqing was causing trouble, and Su Qingqing thought Shen Yan was brainless), to being forced to form a team to investigate the case. As the case deepens, they discover that the shadow puppet case is just the tip of the iceberg. Behind it lies a series of conspiracies involving secret treasures from the previous dynasty. In each case, there is a "mathematical code" that Su Qingqing can understand and a "Jin Yiwei secret code" that Shen Yan can see through. The two fought against each other and rescued each other along the way. They had to battle wits and courage with weird murderers such as "shadow ghosts" and "puppet masters", and also had to deal with the blame-shifting routines in the officialdom. In the end, they not only uncovered the mastermind behind the scenes, but also became the "least compatible but most capable" crime-solving partner in the Ming Dynasty.
