In the first year of the Tianqi reign, government agencies thrive while old and new factions compete for power, and scheming and disorder spread. Shen Wen is a scholar from Qinan Prefecture with a gift for carpentry. One day, while on the road, he is swept without meaning to into the theft of a royal treasure, and the incident brings him into contact with Mu Siqing, an Embroidered Uniform Guard commander. Shen Wen learns that the treasure the Guard is chasing is the Six Harmonies Beast Diagram, the same diagram that led to the slaughter of his whole family. The diagram holds secrets of the imperial court. Set on finding the person who killed his family and on uncovering what the diagram conceals, Shen Wen resolves to infiltrate the Northern Garrison in secret and dig out the truth about what happened back then.