This is the story of a late budding romance that came across hazards. Yeon-Woo and Seon-Jae got a marriage agreement lasting 100 days. Unexpectedly, Seon-Jae suddenly passed away on the day that document expired. At that time, their ‘real’ marriage has really just begun. Yeon-Woo, who is deep in sorrowfulness, is given an opportunity to turn back in the time of 100 days before and she made up her mind to prevent the death of her husband.