Princess Luo Yu of Xia State fell in love with Si Nanping, the major general of Song State who welcomed the marriage ceremony team to Beijing on her way to the Song Palace for marriage. The two of them worked hard to suppress the love in their hearts for the sake of their respective missions. Princess Luoyu was in danger along the way, and Si Nanping protected her from fatal disasters. At a time when everyone thought Princess Luoyu was about to die soon, Si Nanping and Princess Luoyu confessed their love for each other and made an oath to stay together forever and ever. When the two of them wanted to give up everything in front of them and leave the marriage team to become the most ordinary couple in the world, Luo Yu discovered that her brother, Prince Li Liang of Xia, in order to preserve his position in the summer palace, had communicated with Qin Yang, a traitor of Liao Dynasty, and secretly wrote a letter to frame a member of the Si family for committing adultery with the Xia Kingdom. In order to save the Si family from being framed by Liao traitors and prevent the possible war between Song and Xia caused by Prince Xia Li Liang's visit to Liao, Luo Yu reluctantly gave up leaving Si Nanping and decided to enter the Song Palace in person, trying to prevent the tragedy that was about to happen at the cost of ruining her life's happiness. Luo Yu and Si Nanping were lovers who were in love. They fell in love with each other and couldn't stay together because of their inherent missions. Luo Yu gradually became a queen of the Xia Kingdom from an innocent little daughter. No matter how her status changed, the two never forgot their promise to each other and worked hard for this all their lives.