Jessica's heart was broken by the only girl she has ever loved. After 2 years of taking her internship overseas, she decided to take her last year as intern back in Korea. She had no idea she will see the person who broke her heart into pieces.

Yoona is a gifted doctor. She never wanted to hurt Jessica. She loved her, she really did but she had to break up with her even if it was against her will. But meeting Jessica again sent her heart fluttering once again, something she never thought it will ever do again after that break up.

Yuri is Yoona's step sister. Her mom remarried Yoona's father and the two just clicked right after. She's a successful Engineer leading the seemingly perfect life but that was until her greatest regret came into her life once again. This time, she is sure of what she wants and she will never make the same mistake ever again.

Tiffany is the bubbly type who always keep the bright smile on her face but behind that facade is a fragile heart afraid of getting hurt again.

By fate the lives of the 4 of them intertwined. Will they able to fix their mistakes and live happily ever after? Or was ending their relationship before the right thing to do and should be kept that way?