The story begins with Tiana, a noblewoman, entering into a political marriage with Eugene Gardolf, the Prime Minister. Her grandfather tasked her with two duties: supporting Eugene's political standing and educating his daughter, Fine, to be a suitable empress. On her wedding day, Tiana added a third personal mission: to dispel a sorrowful shadow hanging over the Gardolf family using her unique abilities.
Three years into the marriage, Tiana had fulfilled her first duty. Eugene, a man of talent who rose from a humble background, had solidified his position as Prime Minister, likely with Tiana's influence. Though trust had grown between them, love was absent, and their marriage was purely nominal. As the agreed-upon time for divorce approached, Tiana proposed it, but Eugene refused, asking for a postponement until Fine's royal marriage was secured. Fine, a beautiful and well-educated thirteen-year-old, deeply respected and loved Tiana. Eugene implored Tiana to stay by Fine's side until her wedding, which typically occurred around fifteen or sixteen. Tiana, who had grown fond of Fine, agreed, hoping to fulfill her third mission within the remaining three years.
The narrative then shifts to Ines, a spirit who is trapped in a place she doesn't belong, unable to move on due to an unknown lingering regret. She encounters a kind woman, Tiana, who addresses her by name and asks about her regret. Ines, surprised to be acknowledged, admits she doesn't know what keeps her there, her memories and sense of self having faded over time. Tiana explains that Ines's presence is not good for her or the living, and that she is there not to erase Ines's regret, but to help her move forward. Ines finds herself trusting Tiana, sensing that Tiana's purpose aligns with her own unspoken desires.
Tiana's presence has helped Ines regain her memories and emotions. However, Ines is now angered by the current situation, despite Tiana's calm demeanor. Tiana is focused on preparing dresses for Fine's upcoming wedding, seemingly oblivious to the underlying tension. Ines expresses her frustration, questioning how Tiana can remain so composed. Tiana, however, states she is aware of everything and reassures Ines that things will be alright, referencing the approaching "light" that signifies Ines's eventual departure. Ines realizes that Tiana's arrival has helped her recall her regrets, and while Tiana isn't there to erase them, Ines fears her own lingering feelings might increase.
Eugene returns home, greeted warmly by Fine, who shares a loving exchange with him. Tiana, as the nominal wife, offers a polite bow. Rosetta, a sixteen-year-old girl staying with the family, walks alongside Eugene and Fine, subtly displaying a sense of superiority towards Tiana, which Tiana acknowledges but does not react to, as Eugene permits it. Ines, visibly upset by Rosetta's presence, expresses her dislike, but Tiana calmly advises her to endure for a few more days, focusing on Fine's wedding preparations.
Eugene visits Tiana in her room, finding her in her nightclothes. He informs her of his intention to bring Rosetta to a Marquisate party and asks Tiana to arrange for her cousin, Alex, to escort Fine, implying he will escort Rosetta. He also requests Tiana's assistance with Rosetta's preparations. Tiana agrees, though she senses the underlying tension and the unspoken anxieties of the household staff regarding the shifting dynamics.
Later, Tiana is preparing to leave for her family's estate. She reflects on her marriage, which was a political arrangement, and the impending public announcement of Fine's royal engagement, which signals her own departure. As she examines jewelry, Ines appears, urging her to go to Eugene's room. Tiana finds the door to Eugene's private chambers open, with Rosetta and her attendants rearranging furniture. Tiana intervenes, asserting that nothing can be done without Eugene's command. Rosetta protests, claiming her family's high-quality furniture is being discarded, and insults Tiana's position as wife. Tiana, angered, declares she will be leaving for her family's estate and requests a carriage, leaving Rosetta's fate to Eugene. Fine, who has witnessed the confrontation, expresses her reliance on Tiana.
Tiana is warmly welcomed back to her grandfather's estate. She reflects on her upbringing and the influence of her grandmother, who taught her everything she knows. Her grandfather had arranged her marriage to Eugene, hoping she would support him and Fine. Tiana feels her mission is nearing its end. Later, Eugene arrives at the Marquisate, demanding Tiana return with him. He reveals he has sent Rosetta back to her family and insists on taking Tiana home, stating he cannot imagine his life without her. He confesses his love for Tiana, acknowledging his past neglect and his desire to be with her. Tiana, overwhelmed, accepts his confession, and they agree to return home together.
Eugene, reflecting on his past marriage to Ines and his subsequent relationship with Tiana, realizes his feelings for Tiana have grown beyond a political arrangement. He recalls his regret over his inability to express his love to Ines and his subsequent devotion to Fine. He acknowledges Tiana's unwavering support and her unique role in his life and Fine's. He decides to pursue a genuine relationship with Tiana, despite her initial reservations.
The next day, Eugene visits Tiana again, bringing her a bouquet of flowers. He expresses his feelings, admitting his past mistakes and his desire to build a future with her. Tiana, initially overwhelmed, eventually reciprocates his feelings, accepting his love and agreeing to return home with him.