Substitute Daughter: Accidentally Provoking a Mad-Descent Plutocrat

Ella, a girl from the bottom rung of society, is forced to take the place of a missing heiress and become engaged to the fifth young master of a chaebol family in order to save her critically injured brother. However, she inadvertently stumbles into the territory of the family's most dangerous "madman"—the second master, Theodore. Amid pressure and probing, she discovers that behind this impostor game lies a shocking conspiracy capable of overthrowing the entire chaebol empire.