Sun-joo is busy preparing for her upcoming wedding. But her fiancée Ji-hoon plans to go on a business trip with the beautiful writer So-ra who turns out to be Sun-joo’s best friend from before. With all the doubts and jealousy, she lies to So-ra and accompanies her in place of Ji-hoon. But on their way she realizes that the memory about their dearly friend Yeo-eun, who died in a tragic accident, are quite different. What really happened to them? Can they reveal the untold truth?