Su Yingying, daughter of loyal Chief Minister Su, marries second prince Xie Yuheng, whose troops later massacre her family on treason charges. Xie Yuheng becomes crown prince. Three years later, Su Yingying, with seventh prince Xie Yi’an, poses as his maid Suying to uncover truth. They link a counterfeit banknote case to Chief Minister Su and Xie Yuheng, leading to a deeper investigation. Initially at odds, they grow close while exposing Xie Yuheng’s conspiracy for power through fake banknotes, bribes, and assassinations. Xie Yuheng, not of royal blood, frames Su for treason to cover his crimes.