Because of a misunderstanding 8 years ago, Jung Da-ae and Lee Han-eol are mortal enemies. To make things worse, their siblings get married making these two in-laws! But then the bride and groom are killed in an unfortunate accident. In a moment of mourning and arguing in the middle of the road, Jung Da-ae and Lee Han-eol are hit by a truck, killed and transported back to when they were in high school! Is this their chance to fix everything?!