Banished female physician Shen Yungui is exiled to Youzhou with her mother and younger sister. Hanging by a thread, she is saved from the snow by border garrison soldier Wei Zheng, who pulls her back from the jaws of death. Armed with medical skill and an abacus in a broken temple, she sews up Wei Zheng's wounds and plots for him, step by step pushing him from a rough soldier to the position of Southern Camp Thousand-Household Official. Facing Feng Shi'an, the Thousand-Household Official who has entrenched the garrison for years, the two operate one in the open and one in the shadows. Borrowing military grain, auditing accounts, and laying secret lines, they peel back the corrupt ink-black curtain layer by layer. Winds and snow cannot snap the branch, and amidst the chaos, two hearts draw closer and closer—she guards his life, and he protects her good name.