On the birthday of Yan Xun, Regent of Great Yong, he receives an ancient drum engraved with red plum blossoms. Astonishingly, its pattern is identical to the birthmark on the shoulder of his legitimate wife, Princess Zhao Zhaohua. That very night, a severely wounded woman is abandoned outside the prince's residence. She bears half of the same plum blossom mark on her shoulder. Yan Xun begins to suspect that something is terribly wrong: the princess currently living in his residence may be an impostor. Following the clues, he gradually uncovers a conspiracy orchestrated by the Empress Dowager and discovers that Zhao Zhaohua was persecuted and driven into a desperate situation. Devastated by the loss of his loved one, Yan Xun vows to uncover the entire truth. Relying on his own strength, he gathers evidence and resolves to make everyone responsible for the crimes pay the price under the law.