After Jiang Ling falls off a cliff and travels through time, her stepmother and legitimate elder sister force her to take her sister's place in an arranged marriage. She is sent far away to the northern frontier to marry Murong Jin, the Prince of Dingbei, who is gravely ill and on the brink of death. Using drone reconnaissance, she anticipates enemy attacks. With surveying data, she discovers a salt mine and resolves a military supply crisis. She preserves footage of corrupt officials colluding with the enemy and sends it to the capital to expose their conspiracy. When her drone becomes unusable, she hand-draws a map of the entire territory and teaches soldiers and civilians to identify mountains, rivers, and strategic routes. When the Jiang family demands a divorce and Situ Heng raises an army to besiege them, she relies on her strategic knowledge of the terrain to suppress the rebellion. After the new emperor ascends the throne and recognizes her achievements, she and Murong Jin govern the northern frontier together, winning the people's wholehearted support. In troubled times, the people's trust is the strongest source of strength.