Taemin Lee is in love with Sulli Choi. Well, actually, he just loves the very idea that is her.

His luck brought him to live across the street from the beautiful girl and so, as it goes, they became good friends. In high school, their lives started running in two very different circles but Taemin never failed to forget Sulli and in turn, she never forgot him. 

One night, Taemin has an unlikely run-in with Sulli and the next day; Sulli is all but an idea.

As Taemin, with the help of his friends, follows the tracks left behind, he starts to realize that he's been in love with an entirely different person.