Rafina is a noblewoman who, after striking her head, regains memories from a previous life. Before she can make use of this reawakened awareness, she is branded the "Poison Flower of the Capital" — a false reputation for wanton behavior engineered by her stepsister, Katrina. Katrina steals Rafina's fiancé and has her cast out of the family. Rafina is then forced into a political marriage with Berion, the "Monster of the Borderlands," a frontier count rumored to be a terrifying beast.

Upon arriving at his remote estate, Rafina finds that Berion's monstrous appearance is the result of a curse, and that beneath it he is a gentle and considerate man. Initially wary, she gradually comes to trust him, and the two begin to grow closer. Rafina uses the knowledge from her past life — particularly her understanding of chemistry and mechanics — to improve daily life in the territory and to help Berion. A turning point comes when she builds a primitive camera and uses it to temporarily return Berion to his original human form, deepening the bond between them.

The story proceeds through three acts of growing intimacy, mutual discovery, and the slow lifting of the curse. In the final arc, the couple receives an invitation to a royal ball in the capital. Rafina returns to face her biological family and the stepsister who betrayed her, while Berion confronts the political schemes and prejudice that led to his curse. The narrative concludes with the couple's love fully acknowledged, the curse broken, and their place in both the frontier and the capital secured.