Ri Sun, originally birthed as a maid into the Jiang Family - one of the richest families in Yin Dynasty, North - discovers she is the real daughter of Lord Jiang but was swapped unfairly at birth. However, her discovery comes too late as the real perpetrator who had killed her mother murders Lord Jiang and frames her for it.
Hence, Ri Sun becomes a slave and a murderer overnight, set to be executed. Despite her fruitless attempt to clear her name and have her revenge, Ri Sun faces death by beheading.
Before she is beheaded, she holds onto a moon stone and doesn’t let go even after her body got buried.
Several days later, Ri Sun is rebirthed into the Grand King of Yin Dynasty, the North’s mistress and his favorite. Thus, she is given a chance to get her revenge on those that had wronged her. However, what seemed like a revenge mission transforms to fighting for the country and fighting her enemies when the Grand King suddenly makes her the queen of the north, the highest authority in the Yin Dynasty.
Hence, she struggles to balance her duty as the queen of the north and real purpose for her rebirth.