Bai Tian, as a people's teacher, is seen by others as a winner in life. She has a respectable job, a kind heart, a beautiful face, and a gentle and considerate partner. But nobody knows that she has a secret. This secret is hidden in her partner's sister. "She has been playing the role of a saint all her life. Perhaps the only dishonorable thing in her life is falling in love again." One-sentence summary: Only nighttime remains. Theme: Daytime will understand the darkness of night.