Jin-heon is the son of a wealthy hotelier (Na Moon-hee), and his mother constantly nags him about succeeding her in the hotel business. She also keeps setting him up on matchmaking dates, saying his niece Mi-joo (Seo Ji-hee), who hasn't spoken a word since the childhood trauma of her parents' deaths, needs a mother figure. When Sam-soon finds herself in need of (approximately ) to prevent the foreclosure of her mother's house, Jin-heon proposes a deal: in exchange for the money, she agrees to become his pretend girlfriend. They draw up a complicated contract, of which the most important stipulation is that they should never fall in love for real. But as they spend more time together, Sam-soon and Jin-heon grow closer and gradually fall for each other. But just when things are going well, Jin-heon's ex-girlfriend Yoo Hee-jin (Jung Ryeo-won) returns from the United States.