After her elder brother ascends the throne, Princess Felicia of Grancalst is shipped off to a distant kingdom as a political bride. On the journey, her memories of a previous life flood back, and she realizes with horror that she has been reincarnated into an otome game. In that game, her new husband, Crown Prince William, is meant to fall for a saintess summoned from another world, and Felicia herself—cast as the inconvenient obstacle—is fated to be executed. Determined to dodge the death flag, she resolves to quietly vanish, planning to shed her royal identity and live as a commoner using her one true skill: the knowledge of medicinal herbs and poisons gleaned from her past life.

But William refuses to let her slip away. He showers her with affectionate words and gestures, leaving Felicia baffled and suspicious. Is it a trap? A cruel game? The more she tries to create distance, the closer he draws her in, all while the court and its servants treat her coldly, favoring the awaited saintess. As Felicia struggles to navigate the palace's intrigues, she also bonds with an eccentric maid and a loyal beast‑like guard, and gradually uncovers William’s own hidden past—a childhood marked by emotional neglect, from which Felicia’s stubborn brightness once saved him.

The story’s notable arcs include the poisoning incident, where a bitter servant tries to kill Felicia, forcing William to finally confront the rot in his household; the arrival of the actual saintess, a hardworking girl who turns out to be a kind rival rather than a villain; the introduction of William’s scheming cousin Rosalie, who challenges Felicia for the position of consort; and a later confrontation with a silver‑haired young man named Alphonse, who wields miasma and harbors a grudge against William tied to a past betrayal. Through these trials, Felicia grows from a frightened escape artist into a resourceful herbalist who commands respect, while the romance between her and William shifts from mutual misunderstanding to genuine devotion.