A woman with a gift for lying is employed by a chaebol heir to act as his long-lost cousin. To keep up the charade for his family, the two must live under the same roof, but their growing attraction to each other poses a problem for pretending to be relatives.
When Seol Gong Chan meets the lively and beautiful Joo Yoo Rin, he finds out that she has connections to his missing cousin, whom his grandfather has been searching for. He asks Yoo Rin to lie about being his long missing cousin until he can find his real cousin. She says yes, but soon their feelings for each other get in the way of their plans. Gong Chan's cousin, Seo Jeong Woo falls for Yoo Rin while Gong Chan's ex-girlfriend, Kim Se Hyun, a pro tennis player, tries to win him back. Will the two ever tell each other how they feel? Will Gong Chan ever find his real cousin?