The male protagonist and the female protagonist got pregnant after a one-night stand. They met five years later. In order to save her mother who was in pain, she signed a marriage contract with the male protagonist. As long as she married him for three years, he would bear all the mother's medical expenses. To save her mother, the female protagonist married into the male protagonist's family. The male protagonist lied to the family that the baby was their son. At this time, their first love had returned again. What kind of love sparks will arise between them...