Set in the Ming dynasty, the series follows Zhu Wushi, tasked with forming a secret service to protect the Emperor. He recruits four elite agents—Duan Tianya, a skilled martial artist; Shangguan Haitang, an intelligent and resourceful woman; Guihai Yidao, a master of the dao seeking vengeance; and Cheng Shifei, a former thief with powerful inherited skills.

Locked in a rivalry with the Eastern Depot led by eunuch Cao Zhengchun, the agents work to protect the monarchy while uncovering deeper conspiracies. As Zhu Wushi’s true ambitions unfold, the agents must confront betrayal and save the Emperor.