At the birthday celebration of Leocadio, the third prince of the Seiras Kingdom, a scandal erupts. The eldest daughter of the Cortez viscount family, the stunningly beautiful Amaria, was supposed to be publicly announced as the prince's fiancée. Instead, she meets a guest at the celebration—a prince from a neighboring country—and falls into a whirlwind romance at first sight, ignoring her intended royal betrothed entirely. As the royal family and the viscount's household grow pale with embarrassment, all eyes turn to the viscount's second daughter, Priscilla. She realizes that the only way to save face is for her to take her sister's place. The prince, left with no other option, declares that Priscilla must become his fiancée instead. What began as a reluctant arrangement between a prince and the sister of his runaway betrothed unexpectedly leads Priscilla to accompany Leocadio to his frontier territory. As she is introduced to the people of the domain as the prince's future bride, the two gradually grow closer and begin to develop a genuine bond. Just as their relationship deepens, however, Amaria—who was supposed to have married the neighboring prince—unexpectedly returns, bringing new complications. Priscilla, a pragmatic and level-headed young woman who never expected to become a princess, must navigate the shifting dynamics of her sudden engagement, her growing feelings for Leocadio, and the challenges that arise from her sister's reappearance in the frontier land where she hopes to find her own happiness.