After a young woman in modern-day Korea falls asleep, she awakens as a newborn baby in a lavish but lonely palace. She quickly realizes she has been reincarnated into the world of The Lovely Princess, a romance novel she once read. Worse, she has become Athanasia de Alger Obelia, the forgotten and ill-fated princess who is ultimately framed for a crime and executed by the order of her own father, the cold and tyrannical Emperor Claude.

Armed with the knowledge of her tragic future, the infant Athanasia decides to completely avoid her father to escape her predetermined death. Her first plan is to remain hidden in the Ruby Palace, hoarding valuable treasures to fund a future escape from the empire. However, fate intervenes when she accidentally meets Emperor Claude at the age of five. Instead of being punished, her unintentionally adorable behavior piques his interest. Forced to abandon her initial plan, Athanasia adopts a new and far more dangerous strategy: to charm her way into the heart of her murderous father, making herself so precious to him that he could never hurt her.

The story is set in the opulent and politically treacherous Obelian Empire, a world of royal etiquette, magical intrigue, and cutthroat noble society. As Athanasia grows up, she must carefully navigate her relationship with the volatile Emperor Claude, a man haunted by a dark past and the loss of his beloved wife, slowly thawing his icy demeanor through sheer persistence and affection. Her struggle for survival becomes more complicated with the arrival of Jennette Margarita, a gentle and kind-hearted girl who is the true heroine of the original novel. As Jennette is welcomed into the palace as Claude’s other daughter, Athanasia must contend with the shifting family dynamics and the political machinations of nobles who wish to use Jennette to usurp the throne.

Throughout the narrative, Athanasia’s journey diverges further from the original plot. She forms crucial alliances, including with Lucas, a powerful and ancient mage who becomes her tutor and protector, drawn to her unique destiny. She also becomes entangled with Ijekiel Alpheus, the charming and gifted son of a powerful duke, who becomes a close friend and potential love interest. Major arcs follow Athanasia’s efforts to earn the nickname "the Lovely Princess" from her father, her social debut into high society, and her desperate attempts to prevent the catastrophic events—including a poisoning plot and a dark magic conspiracy—that lead to her execution in the original story. As a shadow from Claude’s past threatens to destroy the empire, Athanasia must use all her wits and charm to protect the family she has come to love and rewrite her own fate.