Ji-hae and Soo-kyoung are friends attending the same university and both have a crush on Sang-min who is in their drama club. The more clamorous and outgoing of the two, Soo-kyoung, asks Ji-hae to do her a favor – write a love letter to Sang-min. Ji-hae pours out her own feelings for him on paper, but sadly in her friend’s name. Touched by the letter, Sang-min is attracted to Soo-kyoung, and Ji-hae, feeling uncomfortable and even guilty, tries to avoid him. And yet by coincidence or by fate she keeps running into him. Ji-hae has lived alone with her mom since her childhood, when her dad unexpectedly passed away. Her mom is now on a trip abroad, and to wile away her solitude she starts cleaning the attic. There Ji-hae finds a secret box, in which her mom kept the memorabilia of her first love story of some decades past. Summer in 1968… Joon-ha is visiting his uncle’s home in the countryside during his summer vacation. There he meets Joo-hee and falls in love at first sight. One day, the lovely Joo-hee secretly asks Joon-ha to escort her to a haunted house in the village. Happy and excited to be at her service, Joon-ha meets her at their promised spot. But in an unexpected storm, the two lose their boat and barely manage to return home at a very late hour. Joo-hee gets into big trouble for this incident and is sent back to Seoul. Having parted with Joo-hee without a word of farewell, Joon-ha spends the rest of the summer heavy-hearted. With summer vacation being over Joon-ha also returns to Seoul. At school, his classmate Tae-su asks him to write a love letter to send to a girl. And who would it be but Joo-hee, Joon-ha’s dream girl. Unable to confess his own summer love story, Joon-ha reluctantly complies with his friend’s request.