Faith

Faith depicts the love between a warrior of the Goryeo (Korea) era and a female doctor today. It shows that their love transcends time and space.

King Gongmin (Ryu Diok-Hwan), who had long been held hostage by the Yuan or China, becomes king of Goryeo (Korea). He marries Princess Nogug (Pak Se-yang), Princess Yuan. Choi Young (Lee Min-ho) and his entourage take King Gongmin and Princess Nogug from Yuan to Goryeo. Choi Young was the protector of King Gonmin of the Goryeo Dynasty in the mid 1300s, 1352. He was 29 years old and had no regrets in life and no desire for women or money. His hobby is sleeping. As a brave captain and strategist of the Woodalchi Warriors, he is not afraid of death.
On the way to Gorio, the group stays at a rest house. A group of assassins break into the inn and attack their group. As the fight unfolds, Princess Nogug is beheaded by an assassin. Zhang Bin (Philip Lee), Gorio's most famous doctor, says he can not save Princess Nogug. If Princess Nogug dies, Yuan (China) will completely take over Goryeo (Korea). King Gommin's aristocrat asks him to pray on a mountain near a mysterious light source. When they get there, they see mysterious lights spinning around like a door into a vacuum.

The aristocrat of King Gommin tells the king that swimming lanterns are truly a gateway to a great physician from heaven. King Gongmin tells Choi Young to enter the gate and get a doctor. After entering the mysterious swimming lanterns, Choi Young lies beneath the entrance of a temple. As he leaves the temple, Choi Young is disturbed by strange scenes. He sees modern buildings, contemporary people and cars. Returning to Choi Young Temple, it is actually a traditional village in the center of present-day Seoul and sees a monk walking.
Choi Young asks the monk where he can find the great doctor. Monk tells Choi Young that he can find the best doctors there at the nearby COEX building where a medical conference is being held.

Choi Young walks into the COEX building and enters the Medical Conference Hall. He then enters a conference hall and sees a woman speaking to a large audience. The woman is Dr. Yu Eun-soo (Kim Hee-seon). Yu Eun-soo is a 33-year-old plastic surgeon. Eun-soo was originally a general surgeon but soon discovered that it was a high-paying, low-paying profession and turned to plastic surgery. Her dream is to open her training someday.

After giving her conference, Dr. Yu In-soo walks through the conference hall and inspects the latest surgical instruments on display. Choi Young appears in front of her and asks her to come with him. He says she needs to treat someone who is seriously injured. Yo Yoon-soo refuses to go with a man dressed as a soldier since ancient times. Choi Young, unable to say for sure if she is the best doctor, removes his sword and cuts the neck of a man nearby. Choi Young orders Yu Yoon-soo to save the man. Yu Eun-soo is ridiculed by Choi Young's action but her doctor gives her an instinct and she acts to save the man's life. Choi Young has confidence in Yu Eun-soo. There is a belief that she is indeed the best doctor and that she can save Princess Nogug.

At this point, police officers enter the conference hall and surround Choi Young and Yu Eun-soo. Choi Young summons his own occult powers to wipe out the surrounding police officers. Choi Young takes Dr. Yu-soo back to the temple. On the way, Yu Eun-soo asks Choi Young to let her go, but Choi Young promises to let her go back if she saves Princess Nogug.As they exit the gate, King Gongmin stands in front of Choi Young and Dr. Yu Yoon-soo. They all go to the inn where Princess Nogug is on the verge of death.