As a child, Park Hoon (Lee Jong-suk) and his father Park Cheol (Kim Sang-joong) were tricked and sent to North Korea. After being sent to North Korea, Park Hoon and his father were denied access to go back to South Korea. In North Korea, Park Hoon was trained to become a doctor by his father who was already a famous doctor. He became a genius cardiothoracic surgeon after attending medical school in North Korea. There, he fell deeply in love with Song Jae-hee (Jin Se-yeon). After Park Hoon's father died, he tried to flee to South Korea with Jae-hee, but lost contact with her in the end. Park Hoon was able to flee to South Korea alone.
In South Korea, Park Hoon begins to work as doctor in a top hospital Myungwoo University Hospital. Meanwhile, he found a girl that looks exactly like Jae-hee, Doctor Han Seung-hee, who claims not to know Park Hoon.