Modern office worker Yang Ling unexpectedly transmigrates into the fantastical Dafeng Dynasty, becoming Xu Qi'an, a man trapped in prison while his family faces ruin over a massive tax-silver theft case. Armed with modern thinking and extraordinary deductive skills, he clears his family's name and joins the Nightwatchman Bureau. As dark currents swirl in the royal court and demons, sorcerers, and rival factions clash endlessly, Xu Qi'an solves one bizarre case after another. Gathering a circle of kindred allies, he stands against the court's shadowy conspiracies, upholding justice in a chaotic age—growing step by step amid the vortex of power plays and the supernatural, safeguarding the peace of Dafeng's realm.