Shen family's eldest young lady, Shen Ning, was abandoned in the frontier for ten years, and upon returning to the capital, she immediately faced a canceled engagement and public criticism throughout the city. No one knows that she is actually an ancient great demon who makes a hundred apparitions bow their heads. She opens a medical clinic, catches evil apparitions, solves eerie cases, and step by step tears open the Shen residence's scheming and the capital's dark plots; she also enters into a contract marriage worth eight hundred thousand taels with the sickly Prince of Jin, Yuan Che. One only wants to freely eat every kind of demon, while the other uses the name of the princess consort to protect her well-being, yet they turn a fake play into a real relationship while jointly eliminating apparitions. When the marriage document reaches the heavenly court up above and sounds in the netherworld down below, this transaction becomes hard to end.