Only square land, Yan, Bi, Yi, and Cheng are divided into four parts of the world. Shen Yu, the daughter of the right minister of the Bi Kingdom, has a dignified, virtuous and gentle appearance, and she admires Ji Ying, the son of the Ji family of the four great families. Indiscriminate destruction, an imperial decree, to choose Yi to enter the palace. Jiang Chenyu led the decree to enter the palace because of the helplessness of the family. But she did not want to become the emperor's concubine and die of old age in the court, so she recommended herself and asked to become Zhao Yin's counselor. Zhao Yin for her Fascinated by her courage and insight, she sent her as an envoy to the Kingdom of Cheng, under the guise of King Cheng’s birthday, and secretly stole confidential information. Unexpectedly, the turmoil that rewrote the history of the Four Kingdoms began because of such an inadvertent decision... A twist of fate The gears start to turn: from a naive and pure sentimental girl to a queen who loves the world; from a weak girl who allows mermaids to be a queen who dominates the world... When the country falls, the world will suffer.