Fan Xian is born in the ancient empire of Southern Qing with memories of the 21st century. He lives in a rural town as the illegitimate son of the Minister of Finance, raised by his grandmother. His mother, Ye Qingmei was once a celebrated inventor and the founder of the Overwatch Department, the country's spy network but was killed shortly after her son was born. Fan Xian has since been protected by a blind martial arts expert, Wu Zhu, his mother's bodyguard. He learns martial arts and the art of poison as a child, also assisted by his knowledge from the 21st century. After an assassination attempt, he decides to venture into the capital to find out more about his mysterious mother and why anyone would want to kill him, as he perceives himself to be an unimportant person. He also wants to know why he has memories of a sharply different era.