Set in the early reign of Ming Emperor Wanli, the masked and mysterious Jinyiwei Captain Yuwen Feng serves the eunuch Zheng Cheng in his power struggle against rivals Zhang Juzheng and Eunuch Feng Bao when his investigation into an attempt on the Emperor's life leads him to encounter one Mrs. Wang, the widow of a private security firm owner.

As it turned out Yuwen is in fact a Wu dang disciple by the name of Ling Feng who, 20 years prior was married to Tong Bik, the daughter of one of two prestigious sword smith clans in the capital.

Their lives are uprooted one fateful night when the Tong clan are framed for treason and sentenced to death with all believing to have perished but Ling.

Admiring his swordsmanship, Zheng Cheng (who is the director of the Jinyiwei) offered to spare Feng from execution and provide a new identity in return for his sworn loyalty for the next 20 year after which Ling would be permitted to seek revenge on the Sima sword-smith clan which he is told are responsible for the Tong clan's extermination.

Having accepted the deal, Feng wears a mask to hind his identity while rising through the ranks under Cheng completely unaware that his wife Tong Bik is in fact still alive and also seeking revenge on the Sima clan.