Every person has a heart. Your life depends on that small organ, which is around the size of your fist. A heart surgeon fellow, Park Tae Soo, has to save his mother, who awaits her heart transplant. But Choi Seok Han is the chief of Chest Surgery Department, and he decides if Tae Soo will maintain his status or not. They work at Taesan Hospital’s Chest Surgery Department, and every day is like a battle. Chest Surgery Departments are where the quality of university hospitals are decided. The skills of residents are proved there. Some people die in the operation room, and those who do not have confidence in their skills avoid doing surgery. People’s lives depend on it. But among the doctors of Chest Surgery Department, those who have the skills required have no power while those who have power are not skilled enough. This makes them compete against each other in an ugly way even if the lives of patients depend on them.