Once a bright young noblewoman, Morenet of House Idira was shattered when her childhood fiancé Prince Alexis cruelly declared he would never marry an ugly woman and replaced her with her younger sister. Unable to forget the insult and unsure which part of her was considered hideous, she developed a deep complex and began covering her entire body in iron armor. Retreating from society, she now lives alone in a secluded forest castle, spending her days studying magic while earning the mocking nickname the Heavy Armored Lady from the outside world.

One day, Prince Alexis and his sardonic yet protective knight Percival unexpectedly arrive at her doorstep. The prince explains that he has been struck by a curse of terrible bad luck, forcing him to repeatedly stumble into swamps and endure endless misfortunes. Believing Morenet cast it in revenge, he begs her to break the spell. Morenet insists she remembers nothing of the sort, but reluctantly agrees to help, setting off on a journey with the prince and the sharp-tongued knight.

Their travels lead them to a neighboring country, where they encounter the eccentric witch Gina, her feline familiar Concetta, and begin to uncover a much larger conspiracy behind the curse. As the investigation deepens, the tangled web reveals not only the involvement of Prince Alexis's ambitious younger brother and Morenet's own sister, but also a painful family history that forces all of them to confront long-buried wounds. Over the course of the journey, the initial mistrust between Morenet and Percival slowly gives way to a burgeoning romance, while Prince Alexis must face the consequences of his past cruelty. The final confrontation brings the truth of the curse to light and offers a chance for redemption, healing, and a future none of them expected.