The ancient demon Sijing (the heroine) wakes up in the modern city after sleeping for thousands of years. In order to adapt to society, she disguises herself as the proprietress of an antique shop called "Wangchuan". Due to a bizarre case of serial mummies, she was targeted by the criminal investigation forensic doctor Bo Yanchen (male protagonist) who has an extremely rare "pure yin constitution". Bo Yanchen is not only a top forensic doctor, but also the heir to the powerful Bo family in Beijing. He has been coveted by evil spirits all year round because of his special physique, but Si Jing found that being close to him can quickly restore his evil powers.
The two reached an agreement: Si Jing used metaphysical means to help Bo Yanchen solve unsolved cases that modern science could not explain, while Bo Yanchen provided "yang energy" and used secular power to solve Si Jing's troubles. The main theme of the plot is "metaphysics to solve crimes + slap in the face of fake masters + wealthy families". Si Jing crushes all villains with absolute force. From being mistaken for a charlatan at first, to being worshiped as "fairy sister" by the entire network, the two finally revealed the bond that spans thousands of years and join forces to suppress the evil forces that attempt to subvert the world.
