김희선
After King Gongmin of Goryeo (Ryu Deok-hwan) marries the Yuan princess, Noguk (Park Se-young), they return to Goryeo. On their way, they are attacked, and the queen is fatally injured. According to the advice of his royal advisor, the king orders the Captain of the Royal Guard, Choi Young (Lee Min-ho), to pass through a mystical portal ("heaven's gate") and find the "heaven's doctor". Choi Young travels to the future and brings back Yoo Eun-soo (Kim Hee-sun), a modern-day doctor from Seoul, to save the queen's life. He promises that he will return her to her world once she saves the queen, but the royal advisor schemes and persuades King Gongmin to force Eun-soo to stay as she can be useful to him.