Rival investigators Cui Buqu and Feng Xiao embark on a diplomatic journey westward, hoping to build a key alliance that will stand against the power-hungry Eastern Khaganate. But they get more than they bargained for when they stop to rest at the oasis city of Qiemo, where they find a haunted inn, a beleaguered Sui magistrate, and the city divided between two powerful self-styled rulers.

Despite their larger mission, Cui Buqu has an audacious idea-one that will turn the city upside down and bring Qiemo back under Sui control if he succeeds. Even Feng Xiao must admit that, while Cui Buqu's schemes are outrageous, there's something increasingly intriguing about this sickly chief of the Zuoyue Bureau. Yet more is at stake in the city than petty power struggles: as the investigative duo digs into the underbelly of Qiemo, they uncover evidence of a conspiracy that stretches across Great Sui and beyond.