As a child, Park Hoon (Lee Jong-suk) and his father Park Cheol, a well-known surgeon (Kim Sang-joong) were sent to North Korea to conduct an open-heart surgery on Kim Ill Sung to prevent the Second Korean War. After being sent to North Korea, Park Hoon and his father were denied access to go back to South Korea. It is revealed that Park Cheol is suing the Myungwoo University Hospital for a serious malpractice case and Park Cheol's friend, Dr Park Choi wanted to take responsibility. However, the director of the Hospital Oh did not want the malpractice case to become public which will ruin the hospital's reputation. As the result, he conspired with Jang Seok-joo, a national security official to make Park Cheol and his son trapped in North 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 while moonlighting as a smuggler, selling South Korea K-pop DVD. 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. At the same time, Lee Sung-hoon, a leading doctor in the hospital plans his revenge against the institution for the death of his father in the malpractice case 10 years ago.
A South Korean who was raised in North Korea after his father was conned into going over to North. He trained to be a genius doctor in North Korea and later defects to South Korea in a bid to live a better life with his lover.
Jae-hee is Park Hoon's soul mate who was separated from him while they were escaping from North Korea; Seung-hee is a North Korean woman and is a specialist in oriental medicine anesthesia.
Park Hae-jin as Han Jae-joon 한재준/ Lee Sung-hoon 이성훈
A genius who graduated from Harvard and became a doctor to take revenge on Myungwoo Hospital for the death of his father in a malpractice case, as Park Hoon's rival.
Chun Ho-jin as Prime Minister Jang Seok-joo, the primary antagonist of the series.
Jeon Gook-hwan as Oh Joon-gyu (Soo-hyun's father and chairman of the Myungwoo Hospital), he is the major antagonist of the series as he responsible for deporting Dr Cheol and his son to North Korea in the first place.
In China, the online streaming rights for drama were sold for $80,000 per episode and the drama was made available for online streaming on both Youku and Tudou where it received 330 million and 50 million views, respectively. As of July 7, 2014 it has been streamed close to 400 million times.[3] Due to the drama's success in China there are currently plans to edit the drama into a film and release it theatrically exclusively in China with an alternate ending.[4][5][6] According to the website DailyNK, which reports on North Korea-related issues, the drama was highly popular among North Korean youth who would obtain it illegally at the jangmadang (markets).[7]
