Cesia, a commoner working as a servant, has spent the last two years disguised as Selene Diane, the lazy and unpleasant daughter of a viscount, attending the Royal Academy in her place. Her motivation is purely transactional: a large sum of money promised upon successful graduation, which would secure her future. The arrangement comes with daily struggles, as she must navigate the minor bullying from noble ladies while also managing her demanding work at the viscount's mansion. The story's central conflict ignites just before graduation when Cesia is tricked by the same nobles who hired her, and her promised reward vanishes completely. Furious and betrayed, she vows to get even, though she has no clear plan for how to achieve this revenge.

At this pivotal moment, she encounters the second prince of the kingdom, Marcus. Recognizing her situation and her fierce, stubborn nature—which he compares to a stray cat—Marcus offers to help her. This partnership quickly escalates beyond simple revenge, pulling Cesia into dangerous government work where her life is repeatedly threatened by corrupt nobles and dangerous schemes.

The main characters are Cesia, a straightforward and blunt young woman with low self-esteem and a tendency to blame herself, who cares little for her own well-being. In contrast, Prince Marcus is mischievous and willing to risk his life for his country, though as the second prince, he is not the heir and also struggles with his own sense of self-worth. A notable twist involves Marcus’s secret identity. At the academy, he uses magic to disguise himself as an ordinary noblewoman named Maria, becoming a casual acquaintance of Cesia. Even after Cesia discovers the truth about Maria, she continues to interact with both personas separately, feeling more comfortable and open with the female Maria than with the prince himself.

The initial arc focuses on Cesia’s infiltration of the academy and her subsequent escape from her employers. This leads directly into a revenge arc that morphs into a larger political thriller, taking the story almost entirely away from the academy setting. Following their partnership, Cesia and Marcus work for the government, dealing with threats such as a jealous younger sister of Marcus who is ultimately good-hearted, nobles engaging in decadent and illegal activities, and a particularly evil fiancée of the prince who frames Cesia for a crime. The final narrative arc sees Cesia and Marcus resolve their feelings and confess their love. However, as a commoner, Cesia cannot marry a royal without a title, so she is granted a barony in recognition of her heroism. The story concludes by introducing new obstacles to their marriage, including subtle and clever opponents who wish to see them apart.