The medical drama focuses on the lives of doctors and nurses who are members of an elite medical team from the fictional Gwang Hae University Hospital.

Set during the Silla dynasty, Sam Maekjong is the son of the fallen king and present queen regent, Jiso, but he has been kept in hiding for protection ever since he was a young boy, when his father was murdered. Over the years the powerful nobles have tried and failed to usurp power from Jiso, causing her to grow wary and later even reluctant to hand the throne over. As her son comes of age, she creates the Hwarang, an elite group of male youth who train in fighting and education. Their existence cuts across the existing power factions and Sam Maekjong is amidst their ranks under the false name Kim Ji-Dwi, unbeknownst to other Hwarang members.

Jin-il, Ga-young, Bong-gil, and Min-kyung are teenage runaways who live together as a family. Jin-il is the leader of the group, earning money by selling stolen goods. As it gets harder to make a living for 4 of them, they plan even more dangerous crimes to survive the cruel society where they have no protection from the adults. One day, the kids steal a car from Hyung-Seok, a karaoke owner who illegally uses underage girls as prostitutes. Outrageous Hyung-Seok tracks them down with his men and forces Ga-young to work at his karaoke bar until they pay back for his car. Even worse, the two friends give up making money and now Jin-il struggles alone to save Ga-young…