Song Shizhi grew up in the northern borderlands for seventeen years, yet the capital buzzed with rumors that she was a gentle, refined talented woman raised south of the Yangtze River. Bound by an imperial marriage decree, she disguised herself as a refined lady to marry into the Marquis of Zhennan's estate, eagerly hoping to divorce the heir, Xiao Hanlin, and make her escape. Accidentally, she discovered that the heir's secret room was filled with portraits of her in frontier battle attire. Uncovering the old ties of their youthful encounter, the two joined hands to investigate hidden dangers and protect the peace of the country and family. No longer confined to the courtyard of the marquis's estate, she was willing to be his backbone behind the scenes, braving mountains and seas together to keep their original vow.