Seungwan and Joohyun have been best friends since childhood. Their senior year, Seungwan moves to Canada for college... and only tells Joohyun the week before she leaves. Hurt, Joohyun doesn't see Seungwan off, doesn't answer her texts, and doesn’t open any of her letters. Years later, Seungwan starts getting strange dreams of a world where she reunites with Joohyun, where she is forgiven. She gets strange notes too... “You have seven days with her...” What does it all mean?