Unknown to Everyone

Chae Yeon-ah takes her sick younger sister Sia’s place on a blind date with Seo Jeong-ju, heir to the Sunghwa Group and Sia’s longtime crush. Jeong-ju falls for Yeon-ah and hurries their marriage, and she goes through with the wedding in her sister’s place. After Sia recovers and moves into Jeong-ju’s home, he begins to sense something is wrong in their married life. A slip of the tongue by their father, Chae Chung-soo, reveals that Yeon-ah was deliberately abandoned at an orphanage and kept by her father and sister as a kidney donor. When she threatens to expose them, Chung-soo—who is eyeing a presidential run—tries to have her killed. A hitman’s mistake leaves Sia in a coma instead, and Yeon-ah decides to live as Sia and seek revenge on her family.