Hye Jung is an uncivilized 16-year-old girl who finds her life miserable and nothing worth living (her mom died when she was little), so she never tries in school and always acts impolitely and violently towards others. Her father leaves her for her grandmother to take care of her. Until she accidentally bumps into a man (Ji Hong) while she steals a CD, and later he moves in her grandmother’s house and becomes her teacher at school, her life has completely changed. He discovers that she is intelligent and he tries to keep her back on track. Her grandma wants her to have a good career, and she now believes in her successful future, so she tries to achieve her dream of being a doctor.
Yoo Hye Jung (Park Shin Hye) was a tough bully in school with a prickly personality and always goes wayward. She had many scars from her childhood and through self-preservation, Hye Jung keeps her heart shut away from other people. However, she changes after meeting her mentor Hong Ji Hong (Kim Rae Wong) who plays a key role in transforming her life from a helpless gangster to a compassionate doctor.