Qi Yan, the prime minister’s son of Great‑Qian, feigns idiocy after witnessing the massacre of the Duke‑Protector household. In truth he is Song Qing, the duke’s surviving grandson, biding time for revenge against his poisonous step‑mother. When the Northern‑Di forces coerce the princess into marriage via a martial contest, he defeats their champion and becomes the princess consort. Together with the princess, he uncovers the old conspiracy behind the massacre involving his step‑mother, a powerful marquis and even his birth father. With truth revealed, he restores his surname Song, inherits the dukedom and wishes for lasting peace.