I heard that after I died, I became the villain’s white moonlight.

Sang Nian, a graduate student who failed her thesis plagiarism check, accidentally transmigrates into a cultivation novel after collapsing in despair. She inhabits the body of Sang Yunling, the vicious female supporting character destined to die at the hands of Xie Chenzhou, the tragic male supporting character and the female lead's first love. In the original story, Sang Yunling abducted Xie Chenzhou, subjected him to abuse, and drove him to madness, only to be killed by him in revenge. Sang Nian finds herself bound to Xie Chenzhou on their wedding night, facing his murderous intent. A system named Sixty-six appears, assigning her a mission to conquer Xie Chenzhou's heart within seven months or face death. However, the system is unreliable and often offline, leaving Sang Nian to navigate her precarious situation alone.

Sang Nian attempts to change her fate by treating Xie Chenzhou with kindness, untying his bindings and offering him medicine. She learns that her brother, the City Lord, had forced Xie Chenzhou to swallow aphrodisiac pills and later beat him severely for his defiance. Despite Sang Nian's efforts to protect him, Xie Chenzhou remains deeply distrustful, viewing her actions as manipulative games. His favorability rating toward her is catastrophically low, starting at negative one hundred and twenty thousand. Sang Nian's attempts to build rapport are consistently met with hostility or indifference, as Xie Chenzhou believes she only seeks to use his unique dual-cultivation physique for her own benefit.

A critical turning point occurs when a demon attacks Qingzhou City and kidnaps Xie Chenzhou, mistaking him for a beauty due to his appearance. Sang Nian pursues them into an underground cavern, where Xie Chenzhou is poisoned and near death. To save him, Sang Nian uses all her defensive artifacts and enters his dream, witnessing his traumatic past. She sees his mother abandon him, his years of torture by a man who harvested his body parts for their regenerative properties, and his profound loneliness. In the dream, Sang Nian breaks through the barrier to rescue him, screaming his true name and promising to save him. This act causes his favorability to skyrocket, though it later drops again upon waking.

After escaping the cavern with Xie Chenzhou's help, Sang Nian continues her struggle to gain his trust. She faces the original plot's events, including the arrival of the Xiaoyao Sect disciples who are meant to rescue her. However, the timeline has shifted, and Sang Nian must adapt to the changing circumstances. She realizes that her brother's interference and the original host's cruel actions have created a web of misunderstandings that are difficult to unravel. Sang Nian decides to treat Xie Chenzhou as an equal, offering him genuine care and protection without expecting immediate gratitude. She moves him into her residence, providing him with comfort and safety, hoping to slowly chip away at his defenses.

As the story progresses, Sang Nian uncovers more about the cultivation world and her own role within it. She learns that her congenital heart condition is linked to her transmigration and that her survival depends on stabilizing her relationship with Xie Chenzhou. The narrative explores themes of trauma, redemption, and the complexity of human connections. Sang Nian's determination to change her fate drives her to make difficult choices, often putting herself at risk to protect Xie Chenzhou. Their relationship evolves from one of fear and hatred to a tentative alliance, as they navigate the dangers of the cultivation world together. The story sets the stage for a longer journey of healing and discovery, with Sang Nian striving to rewrite the tragic ending destined for both of them.