On the day of the wedding, Xiao Beiming, the first detective of Daqi, was blamed as a demon night evil, and fled to the lake on the charge of murdering the teacher and treason. Three years later, Xiao Bei returned to the capital, work to won the trust again of his junior sister Zhong Xueman. Together with a group of witty and resolute partners, took life as bait, walked towards death, and teamed up to solve several strange cases, uncover the truth of the night evil, calm the turmoil of Daqi, and protect the common people from harm.