Song Seung Hun was in this drama. He played the role of Jin Hyuk. He is a brilliant neurosurgeon. The drama starts off with him waking up in a forest and seeing a battle between people dressed in historical clothing. He wonders if they are doing a drama shooting and as he runs away from the fighting and everything, he nearly falls of a cliff but gets saved by a man. He passes out when he is saved and it goes back to modern day to show how he came to go back in time.
It all started when a patient came in with a severe brain injury. Jin Hyuk does the operation, to find that inside the brain, was a tiny fetus. He puts it into a jar for further examination later on. However, upon finding this fetus, he has a sharp pain in his head (headache) that passes and then goes away. After that, he celebrates his birthday with his girlfriend, Mina (played by Min Young). On the day that he wanted to propose to Mina, a child got a brain injury and then died. Mina was watching over the two children (one of the child getting injured) and she got angry at Jin Hyuk for not saving the child. Jin Hyuk explained that the child was going to die even with an operation. Angry, Mina goes and drives off, to cool off. He watches her go, letting her have some space to deal with this tragic loss. However, he came to witness her get into a car accident just as she left. She goes into surgery with her last words saying that they will meet again. However, after the surgery, Mina goes into a coma.
Later that day, he goes on the roof, depressed, and is just sitting there thinking about the events that happened. Then a patient walked out on to the roof. It was the patient that Jin Hyuk had done brain surgery on and removed the fetus from. That patient was about to jump off the roof with the fetus in the jar. In the struggle, Jin Hyuk managed to push the patient away but the fetus fell over the building. In attempt to grab the fetus, he falls off the building. The fetus in the jar then turns into a porthole that sends him back in time. He begins to follow the man that had saved him from falling to his death. He was wanted for murdering an official and was in trouble and he was easy to detect from his clothes since he was wearing a doctor's uniform. The man that he was following, was willing to help him, and quickly got him new clothes to disguise himself as a normal commoner. His medical knowledge wins the trust of the Joseon people especially since he knew how to save them during desperate times such as when a guy chokes.
During the time in the Joseon era, he came across a young woman named Hong Young Rae who looked exactly like his girlfriend Mina. Hong Young Rae is extremely skilled in needlework and is from a noble family. She is smart and kind-hearted. However, she is betrothed to her brother's friend, Kim Kyung Tak, yet she does not love him. Kim Kyung Tak, however does. In the meantime, Jin Hyuk is being hunted by an officer/magistrate. (The magistrate was played by JYJ's Jaejoong, by the way). Jin Hyuk also found out that the man who helped him was related to the royal family. Hong Young Rae and Ji Hyuk managed to meet one another when Ji Hyuk found Hong Young Rae's brother out in the street, injured. Upon that, he begins treating people of the era and he even had to develop medical devices and medicine by himself and find new ways to help aid the sick. He managed to become a real doctor with the help of Hong Young Rae. The two start to form a romantic relationship and it is a very odd relationship as the two are from different eras. However, his actions begin to interfere with history and new characters are revealed showing that there are a lot of time travelers. For example, Choon Hong is a mysterious gisaeng who is a time traveler. She falls in love with Jin and she recognizes him from modern time. He had saved her when she was a child (she was the girl with the Rubix cube in the beginning of the drama).
To be honest, this drama bored me at times. So I skimmed through a few episodes. But after watching it, I still felt that it was an okay drama. Also I took into account that there were many people who liked this drama so I don't mean to offend anyone when I say that this didn't make my favorite dramas list.