Shen Changge, a fierce and valiant daughter of a military family, mistakenly marries Pei Shuyan, a poor scholar who puts his own interests first. When she finally comes to her senses, she decisively divorces him. She clears her family's name of the false accusation of colluding with the enemy and joins forces with Marquis of Zhenbei Gu Yuan, an equally formidable ally. Together, they purge treacherous officials from the imperial court and head to the frontier to repel foreign invaders. United by their unwavering loyalty and dedication to serving their country, they protect the mountains and rivers of Great Xia. Through her remarkable military achievements, the heroine is elevated to the rank of Grand Princess Who Protects the Nation. With their shared devotion to the greater good of their country as the foundation, the two find a sincere love in which they stand as equals and remain steadfastly by each other's side.