Lena, an ordinary girl leaving work on a rainy night, accidentally saves Adrian, an injured mysterious man. To escape the humiliating blind date forced on her by her aunt, she asks him to pretend to be her boyfriend, unaware that this seemingly down-and-out man is Adrian Black, the youngest CEO of Blackstone Group. They sign a 30-day fake boyfriend agreement. Amid repeated harassment from relatives and rivals, Adrian fiercely defends her and humbles their enemies every time, and feelings quietly grow between them. Just as Lena opens her heart, the lie that she is merely a substitute for his old flame breaks her heart and drives her away. On the final awards night, Lena stages a comeback with her design talent and exposes the conspiracy. Adrian proposes to her in public. The fake couple becomes real lovers, and she regains her dignity and career.
