Sun-joo is an ordinary office worker at a bank who is preparing for her upcoming wedding with Ji-hoon, an employee at a publishing company. However, Ji-hoon, who has recently become the liaison to popular female author So-ra, does not attempt to show an enthusiastic interest in married life. One day, Ji-hoon causes a traffic accident, and rushing to the hospital, Sun-joo comes face-to-face with So-ra. In actuality, Sun-joo and So-ra were classmates in school. Sun-joo befriends So-ra, with whom she has had no contact until now, suspecting that Ji-hoon's indifference to getting married might somehow be connected to her. This will reawaken a memory of the tragic accident that happened to their mutual friend.....