Song Hye-kyo as Doctor Kang Mo-yeon
A cardiothoracic specialist who works at Haesung Hospital. She is woman who has great abilities but would rather confine herself to the operating . She believes that competence overrules connections but is hit by the harsh reality that she cannot go anywhere without any connections. She is a woman with principles and doesn't fall prey easily to her emotions. Overall, she is the complete package - her speaking abilities are unrivaled, and she is not afraid to admit her mistakes.