His grandfather’s will says he must marry Eunyul, who left him five years ago, and live together for more than a year to inherit control of a company. Although the wound of betrayal is still there, he is forced to start an awkward cohabitation with Eun-yul, who is raising a 5-year-old child alone.

Ever since that fateful rainy day when she was rescued by the handsome Duke Killian Devonshire, Rowena has lived as his mistress. Though she believes that Killian has grown to love her over the past three years, she wants to repay her debt to him and become his equal so that she can stand proudly by his side. But when Killian begins to behave strangely, her trust in him wavers, only for it to be fully broken the day he introduces another woman to be his future wife. Thus, Rowena decides to make some drastic changes to their relationship. But will it be for better or for worse?