One dark and snowy night, after the Sui dynasty has come into power, a convoy sent by the Kingdom of Khotan is ambushed and massacred. Not a living victim remains—and the attackers, along with a chest holding precious treasure in tribute, have vanished. A member of Emperor Yang Jian’s secret intelligence agency, the Jiejian Bureau, pursues the case: the highly successful chief Feng Xiao. Feng Xiao’s investigations take him to Liugong City, where all the top martial powers across the land are coming to meet. But another intelligence agency, the Zuoyue Bureau, has business in the same city—and they have sent Cui Buqu, an ailing but brilliant man who rivals Feng Xiao. These two equally proud men immediately clash and begin a battle of wits, only to hit a dead end on the increasingly cold case. Is the answer to this mystery out of reach, or can Feng Xiao and Cui Buqu find a way to the truth?

A HAUNTING IN THE DESERT 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.

A RACE AGAINST TIMEAfter the long journey to the Western Khaganate, Cui Buqu and Feng Xiao find their diplomatic efforts stymied when they are accused of murdering a Göktürk prince. Thinking on his feet, Cui Buqu requests a single day to crack the case and clear their names. Yet to everyone's surprise, the crafty chief of the Zuoyue Bureau offers himself as hostage, leaving the investigation—and his life—in Feng Xiao's peerlessly beautiful hands. Now Feng Xiao faces a difficult watch his rival perish in the desert or risk his own life in pursuit of the true killer. Time is running out, and unsettling forces are at work within the Western Khaganate. Yet Feng Xiao can't shake the feeling that Cui Buqu may have one final card to play—one that could reveal the truth before it's too late.

ENTER THE LABYRINTHHaving narrowly survived the attempt on his life, Cui Buqu wakes in the cave on Mount Tiannan, where the Thirteen Floors of Yunhai have gathered to meet their mysterious leader. Also awaiting the mastermind's arrival is Feng Xiao, who has come with his own goals and his own plan for escape. Yet before Feng Xiao can put his plans to action, fire breaks out in the cavern stronghold, throwing the assembly into panic. Racing toward the labyrinth that guards the entrance to the mountain, Feng Xiao plunges in—but he is followed by his bitter enemy, the monk Yuxiu, who is determined to take his life. Will Cui Buqu step into the deadly maze to save Feng Xiao? Or will he let his rival perish in the dark?