After king Gongmin of Goryeo marries the princess of Yuan(Queen Noguk), they return to Goryeo. On the way they are attacked and the Queen is fatally injured. According to the advice of his well-wishers, the King orders general Choi-Young to bring heaven's doctor through the heaven's gate. General Choi-Young succeeds by bringing Eun-Soo, a mordern day doctor from Seoul, who saves the queens life. He makes a promise that he'd return her to her world; but King Gongmin, to gain power in Goryeo, forces the doctor to stay back as she can be useful to him.

Later many problems arise when everyone finds out about the heaven's doctor and try to gain her by killing the King and Queen. General Choi-Young saves them by risking his life and helps Eun-Soo to get back to the heaven's gate. Meanwhile they fall in love with each other and are unwilling to part from other.

In order to save Choi-Young, Eun-Soo enters the heaven's gate to collect all her needs and returns to the gate to go back to the General, but due to her lack of faith she ends up entering the period which is 100 years before the period where she left Choi-young and then the gate closes itself. There she spends some lonely years and waited for the gate to open. One day the heaven's gate opens again and she enters into it to reach modern-day Seoul, but being unable to forget General Choi-Young, she re-enters the heaven' gate to find herself 5 years after the period where she left Choi-Young. The General & Eun-Soo find each other once again.