After spending two years teaching in the country, Lee Min Woo returns to a city hospital to complete his residency and face his own uncertainties about being a doctor. Free-spirited and goofy, he is jaded about his job and just wants it easy. He is then jolted out of apathy when a traumatic incident forces him to rethink why he wanted to be a doctor in the first place. The first-year resident Kang Jae In comes from a rich family that owns hospitals, but she just simply wants to be a doctor who can support herself and help others. Both Min Woo and Jae In work in ER under the guidance of Choi In Hyuk, a famously astute workaholic surgeon who puts his patients before himself.