A filmmaker named Siyeon yearns for eternal love but wonders if it is even possible. The weight of eternity and love burdens her until she stumbles upon a 27-year-old letter from her parents, who were convinced of their undying love. Where has the love of Jaesoon and Jaehwan, who once dreamed of eternity, gone? By making a documentary about them, she hopes to learn the secret of everlasting love.