Both FLs are drugged and have no memory of the night they spent with the ML. They have a son as a result of that night, and search for the father, ending up involved with the ML in the process.
Both are mini dramas in which the FLs loses her memory of a night/the past and has raised her young son alone. Unexpectently, she enters into a contract relationship with the ML, later learning he's her son's father.