A troubled Jae Woo begins having nightmares again and finds himself recalling a life-altering accident from many years ago. Although he was successfully able to escape the disaster that stills haunts him till today, his savoir, Ji Hoon, wasn't that lucky, meeting his end there and then. On this day, Jae Woo decides to return to Room 303 at the Hanmaeum Dormitory where Ji Hoon previously lived. Feeling like he still has a lot to say to Ji Hoon, Jae Woo picks up the telephone in the room only to hear what sounds like Ji Hoon's voice coming out from the other side of the line.

Flashback to 2007, Ji Hoon is a student busy preparing for his law exams. One night, as he's returning home, Ji Hoon suddenly finds himself running into a man attempting to kidnap a boy who turns out to be none other than Jae Woo. And while Ji Hoon is able to save Jae Woo from his abductor and prepares to send him back home, Jae Woo is just too afraid to go anywhere for the night.

Upon time traveling back to 15 years, Jae Woo decides to rent a room in the Hanmaeum Dormitory and seize the opportunity to get to know Ji Hoon, However, Jae Woo's sudden appearance in Ji Hoon's life has his friend, Hyung Jin feeling suspicious.

After learning that Ji Hoon is destined to meet his end on the day of his examinations, Jae Woo decides to find a way to stop the tragedy from happening. The first thing that he thinks of is to invite Ji Hoon on a trip...

When Ji Hoon overhears a conversation between Jae Woo and Jae Woo's childhood self, he begins to think that there is something strange about all of this for which he then seeks Jae Woo to clarify what exactly is going on.