Secret Depravity
Fina Castle, the long-lost biological daughter of the wealthy Castle family, grew up in an orphanage. Upon returning home, she discovers that Evelyn, the fake heiress, is having an affair with her elder brother Theodore, and she is only brought back to marry a mafia heir in Evelyn's place. After being humiliated for catching them, Fina gets drunk and has a one-night stand with a mysterious woman named Helena. The next day at the banquet, Evelyn frames Fina for theft, and Fina learns that Helena is actually her stepmother who controls the entire family. Helena saves Fina and persistently seduces her. When Fina sees her fiancé Austin flirting with Evelyn and is publicly rejected at their engagement party, she decides to seek power from Helena.