A locust plague that was rare in a century has invaded the land of Wuzhou. Empress Wu Zetian orders the delivery of relief money to the disaster area, but on the way, tens of thousands of taels of silver are robbed and disappear into butterflies. Detective Dee has ordered his personal assistant Zhao Yuanzhen to investigate the case, while he himself sneak into the civil investigation on streets. In the process of investigating the case, they encounter a suspect, Guan Xiaoqi, who needs to prove his innocence, and are caught in a difficult situation when the relief money is robbed again. The case of the butterflies is a mystery, and the dynasty's power and intrigue are raging.