Xi Zhengyu transmigrates into a book as the evil fiancée of the male protagonist, a destined Son of Heaven, and becomes bound to a system that commands her to commit every kind of evil. On the surface, she completes the system's villain missions by stealing the male lead's opportunities, but in reality, she constantly turns the plot around. She publicly breaks off her engagement at the Emperor's birthday celebration, earning herself a reputation. In secret realms, she takes the male lead's divine sword and spiritual plants, schemes against him and other gifted cultivators, and even subdues Taotie. She also gets caught up in a secret realm containing a Buddhist Venerable's legacy. While dealing with the system, she fights to escape the fate of a supporting character destined to die horribly in the original story.