Do Jin, who received help from Ju Yeon, his girlfriend Ju Eun's younger brother, to prepare for his marriage proposal, wakes up the next day in a house he sees for the first time. Not knowing what's going on, Do Jin asks Ju Yeon about Ju Eun's whereabouts, and Ju Yeon replies, 'My sister is dead'. Explaining that they had an accident on the day of the proposal when they were returning home, Do Jin feels uneasy as Ju Yeon casually mentions Ju Eun's death. Even more confused, Do Jin repeatedly dreams of being intimate with Ju Yeon. Ju Yeon reassures Do Jin, saying he will explain everything in a week, but each revelation only turns everything Do Jin thought he knew... about Ju Yeon upside down.