When a modern forensic examiner's soul transmigrates into the abandoned daughter of a marquis's residence, she is forced to sign a "life-saving marriage pact" with a two-faced marquis. She's a fake heiress carrying a Hidden System, with the golden finger to review memories and see people's luck, but on her wedding night she discovers that her husband's luck stat is a fatal "-999." He's the seemingly gentle and refined Marquis of Zhenbei, but secretly the cold-blooded leader of a demonic cult. When his cold poison flares up, he has to drink blood to survive, and the most compatible "medicine" is the person sleeping beside him.
A marriage contract that begins as a scheme reveals a double conspiracy spanning the cultivation dynasty of Yunhuang Continent and the modern world: a series of blood-draining murders in the marquis's residence, unrest within the demonic cult in the northern frontier, and the mystery behind the true and fake heiresses' identities all intertwine under the Hidden System's missions. She uses her forensic knowledge to solve locked-room mysteries and her modern way of thinking to navigate ancient political schemes. He swings back and forth between using her and falling for her, bringing both sides of his life, the "sickly marquis" and the "demonic cult leader," to life.
Beneath their sweet and angsty romance, which begins after marriage, lies the key to redemption through reincarnation. When the Wu clan bloodline awakens and the truth behind the restoration of the kingdom comes to light, the System interface suddenly displays its final mission: "Host, choose: kill your beloved and return to the modern world, or sacrifice your soul and be trapped in reincarnation forever?"
