After accidentally helping Eunha, who collapsed in the street, Sunyoung unexpectedly marries Eunha's brother Taesung, a rich son in disguise as a janitor. Unaware of Taesung's identity, Sunyoung navigates a newlywed life full of hardship. Taesung secretly helps Sunyoung find her lost sister. While embracing each other's family, they turn their marriage that started with lies into heartfelt love.