On the eve of the wedding of Princess Tang An, the daughter of Dezong of the Tang Dynasty, the Zhusi Rebellion broke out. When Princess Tang An fled with Dezong, she could not bear the fatigue of the journey and fell ill and died. However, her soul traveled through reincarnation and came to the body of the modern girl An An, starting her modern journey. A beautiful and uninhibited brother-in-law, a handsome and caring friend... Tang An is torn between what he should and shouldn't do.