A 32-year-old capable emergency medicine specialist at Sunil University Hospital, Lee Young cannot overcome her colleague's fire and goes on a blind date for the first time in her life.

Unwillingly, while calmly waiting for a blind date, she unexpectedly encounters Mu-yeol, an elementary school classmate and currently the chairman of Sunil Group, the group company of Lee Young's University Hospital.

Muyeol had a special relationship with Lee Young in elementary school, and Lee Young also kept him in the corner of her heart. But Muyeol is proposing to keep the promise he made 13 years ago! What is the fate of Lee Young and Muyeol?