Song Shizhao, a modern medical doctor, accidentally transmigrates into the Great Yan dynasty as the legitimate daughter of the Grand Tutor's household, where she is constantly bullied. Orphaned young, she is forced to take her stepsister's place in the palace to protect her little brother from their stepmother, becoming the new empress to the elderly, frail emperor.
From the moment she enters the palace, she notices the legendary Chief Eunuch Pei Jie. He wields power across the court and is known as the “Nine-Thousand-Year-Old.” His methods are sinister and ruthless, and every court official fears him. Yet in the lonely look he sometimes lets slip, she sees a soul much like her own, trapped in a cage. She begins secretly watching him and learning about him, and her curiosity gradually turns into a feeling she can't quite name.
Not long after, the old emperor suddenly orders her to attend him in bed. She knows that if she becomes pregnant with the emperor's child, both she and the baby will be doomed. So she makes a bold decision: using the portable research System, the “Divine Creation Treasure Casket,” she will conceive with Pei Jie's blood. That night, under the pretense of attending the emperor, she instead bears a child for the man she loves. Pei Jie sees through her intentions, but rather than refuse, he chooses silence and protection.
Nine months later, she gives birth to a prince. From that moment on, Pei Jie finds a legitimate reason to stay by mother and child, under the guise of educating the prince. For four years, he teaches the boy to talk, walk, and read, giving him all his tenderness. The child is his own, yet he can never acknowledge him.
Four years later, the old emperor dies suddenly, and the four-year-old prince ascends the throne. As Empress Dowager, she rules from behind the curtain, joining forces with Pei Jie: she oversees the inner palace while he controls the court, and together they clear the way for the young emperor. And amid this struggle for power,
