"The day he was told he had six months to live... was the day I signed a contract agreement with him." On the day Rita saved a stranger from collapsing on the street, she never imagined he was a billionaire or that her life would take an unexpected turn. She saved Donald Hart, the famous young billionaire. Burdened by an asthmatic mother, a wheelchair-bound brother, and a father who abandoned them but keeps extorting money from her, Rita reluctantly agrees to a contract marriage in exchange for saving her family. Years ago, Donald was inseparable from his twin sister. Their lives changed tragically during a family outing when a car accident claimed his sister's life, while he suffered a severe head injury. Although the doctors assured his family that Donald had recovered, the trauma left him emotionally distant and plagued by survivor's guilt. As an adult, he suffers frequent headaches, dizziness, seizures, and memory loss, ultimately ending up lost on the streets before collapsing. With years of neglecting his health due to guilt of surviving with his twin sister, he was diagnosed with Brain Cancer with only six months to live. However, what matters most is to fulfill his parents' desperate wish of him getting married. He proposed a contract marriage to his saviour, Rita Williams. But his greatest challenge wasn't his short life, but his fading memories. The moment he wakes up, he already forgets about the previous day.