On the eve of her wedding, the Fu family's legitimate daughter vanishes under mysterious circumstances. To save the entire family, they have no choice but to disguise the concubine-born Fu Xiao as her and send him to marry into the infamous Marquis of Zhenye's household. In the eyes of outsiders, he is the gentle, long-suffering, ill-fated “Fu family bride,” but in truth, he is cool-headed and restrained, ruthless and steady-handed, and a master at hiding a knife up his sleeve and keeping his thoughts to himself. Stranger still, while riding in the bridal sedan, Fu Xiao obtains an ancient treasure, the Thousand-Face Bone Mirror. Opened with blood, it can reveal the last wisp of a dead person's final moments, and can temporarily copy another person's voice, bearing, and habits, letting him move through the game under different secret identities. From then on, by day he is the marquis's new bride; by night he is a black-clad investigator. In secret, he also takes on the roles of a traveling merchant, physician, condemned prisoner, and retainer, peeling back the truth behind a string of murders in the marquis's household. But as he follows the clues, Fu Xiao discovers that every time he assumes a new secret identity, another mysterious force is working against him from the shadows, competing for clues, destroying evidence, and using his own identity to set traps in return. That person is both the killer lurking deep within the marquis's household and a better actor than he is. The marriage is a sham, but the attempt on his life is real; the investigation is a sham, but the plot is real. Only when all their identities close in on one another does Fu Xiao understand: from the very beginning, this marriage was a cage custom-built for him by the killer.
