After her father's death in battle and a mysterious warning from her injured brother, Chu Yu vows to uncover the truth. She marries into the defeated Wei family as her late brother's widow to investigate, where she meets the sole survivor, Wei Yun. Though initially guarded, Wei Yun grows fond of Chu Yu, and mutual feelings emerge. Despite the obstacle of their "in-law" relationship, they face dangers together, uncover secrets, and protect their homeland side by side.