Go Siwon's dreams are constantly visited by the clever, beautiful Kang Jinha. In the dream, Jinha keeps on mentioning this "incident" that happened between them but Siwon can't remember anything! And how can it feel so real? Luckily for Siwon, hints about the "incident" start to appear and Siwon is able to regain his memory bit by bit. How will their relationship change at the end of it all?