In the rich and powerful Great Tang, the people of Chang'an enjoy happy lives. But then a severed arm appears openly in the streets, a courtesan dancer has her eyes gouged out, and the wife of the Chang'an magistrate has her tongue cut off. Panic grips the city, and the emperor orders the magistrate to identify the killer within half a month. Magistrate Li Heming, his cousin Li Qingyun, and the guard Yuan Cheng follow the clues, but just as they are about to find the culprit, a eunuch close to the emperor stops them. The killer later dies under mysterious circumstances, and Li Heming resigns. Afterward, he solves one bizarre case after another. As he investigates later cases, Li Heming discovers that they are all connected to the first, and that a vast conspiracy lies behind them.
