Im Sol's life takes a dramatic turn thanks to Ryu Sunjae, a top K-pop idol who lifts her out of a deep personal struggle. Unfortunately, on one tragic night, Seonjae died; and the mysterious watch that used to belong to Seonjae activated and returned Im Sol to their high school days. Armed with future knowledge, she strives to change Seonjae's fate while falling in love with him in the process.
Will Im Sol's love for Ryu Seonjae be enough to reshape time? Or, will time demand a huge and painful sacrifice to grant her heartfelt wish?