Bamboos are swaying under the sun as Lee Rim (Lee Jung-jin) narrates the story of the ancient Silla dynasty. A mystical myth of a bamboo mystic flute "Manpashikjeok" is under King Sinmun's well-kept treasure in the year 682. The magical possession is a symbol from "Memorabilia of the Three Kingdoms."
As he explains the tale, he is seated in a secure room, a table, in front of detective officer Jung Tae-Eul (Kim Go-Eun) and her partner Kang Shi-Jae (Kim Kyung-Nam). Lee Rim's face and his suit satins were covered in blood. Rim testified that his actual age is 70 years old and that his birthdate is 1951. He looks young when he gets hold of the half piece of "Manpashikjeok." He confessed that he killed his half-brother, who was the king during his time.
The questioning between Lee Rim and officer Tae-Eul happened in the year 2020. The detectives were confused about Rim's words when in their data, he died in 1994.
The Kingdom of Corea, 1994
In the Kingdom of Corea, the year 1994, in the winter season, Prince Geum (Lee Rim) invaded the king's palace with his gunned men. He took the ancient "Four Tiger Sword" from its box before heading to the sacred room where King Lee Ho (father of Lee Gon), was standing in front of the "Manpashikjeok" guarded safe glass box. Armed men of Rim shot the guards of the king, overpowering them. Lee Rim reached King Lee Ho and stabbed him with the sword. Rim opened the glass box and took the magic bamboo flute.
Silent steps of small feet covered in blood entered the room. The young boy shouted as he saw his father lying on the floor. Anger led the boy to pick up the sword and hit Lee Rim's hand, which cut the magic flute into two. Lee Rim held the other half tightly while the other one fell to the ground. Rim got mad and strangled the boy with the bamboo flute, and created a wound and bled his skin.
That young boy was Prince Lee Gon (Lee Min Ho).
Amidst the chaos that Lee Rim brought to the king's palace, an armed man entered the room wearing an all-black outfit with a hat and mask on. It was dark, so no one saw his face or identity. He shot each Rim's guard and succeeded in killing most of them. He got near to the Rim when the siren turned on, signaling the outside guards that the palace was under attack.
Rim's assistant insisted that they needed to go to avoid getting caught. Rim tried to look for the other half of the flute but was nowhere to be found. He didn't know that the young prince, who was lying on the floor, reached for the bamboo flute and kept it in his grip.
Rim released the boy when the shooting happened, the fighter who fought with Lee Rim's men saved his life. As Rim fled the place, the fighter went to Prince Lee Gon and checked his pulse. Knowing that the boy is alive, the fighter left the scene as well. The prince, with his other hand, took hold of the ID as his only source of knowing his savior.
The next day, the people of the Kingdom of Corea got news of the king's death. The high court announced Lee Rim as a fugitive and dethroned him. The palace is now making all arrangements for the king's funeral and ceremony for the next heir as king.
Meanwhile, Lee Rim, in his struggle to escape the palace, reached the center of the forest in the middle of the bamboo trees and two tombstones. He hears the music of a bamboo flute and lightning at night. As the high rise stones lit, the magic bamboo flute in his grip transported him to another world.
The Republic of Korea, the present time
In broad daylight, Lee Rim, with his suit full of blood, walked around a new world - the Republic of Korea. He looked around with a puzzled face and tried to recognize the place. He reached a newsstand and read the exact year, the president, and the name of the country. Lee Rim realized he is in a new world and needed to fit in. A restless man bumped and forcibly grabbed Rim's back to face him. Rim recognized his face as his half-brother in the new realm.
Rim entered a dark and filthy room looking at a man sitting in a wheelchair. The sick man is Lee Rim's identity in the new world. He twisted the head of the man and killed him instantly. In this way, Rim will take over the life of the man as his own.
The door opened and a young boy came in. It was Lee Gon's identity in the new world. The boy looked the dead man in the wheelchair and cried. Rim didn't let the chance pass and killed the boy as well. In his mind, the bloodline of the king's family in the new realm is now disposed of. No one will stop him in his future, wicked deed.
The Kingdom of Corea
The ceremony of crowning the heir to the King's throne started. King Lee Gon was wearing the traditional robe and walked the aisle towards the palace with all the high-profile attendees.
Now crowned as the new King, he performed the traditional mourning ceremony for his father. Court lady Ok-Nam supported the young King all throughout. She made special arrangements - a boy younger than him will befriend the young King. Eventually, he became his loyal guard, Jo Yeong (Woo Do Hwan), the son of his late father's good friend as well.
Growing up, young King Gon studied well and became a good leader of his kingdom. He grew up to be a handsome king and very athletic. Jo Yeong remained alongside him and became King Gon's head captain. His only priority in life is to protect the King and to report to court lady Ok-Nam regarding anything about King Gon.
The Kingdom of Corea has a smart and beautiful Prime Minister, Gu Seo-Ryung (Jung Eun-Chae). She manages the government matters and officials of the kingdom. It is also no secret that her eyes are set to conquer the heart of the handsome King. However, what keeps King Gon's mind occupied is to find the fighter who saved his life. The ID that he took from the fighter shows a Seoul Police ID holding the name Ms. Tae-Eul.
King Gon loved the story of the 'White Rabbit With The Clock." He usually reads children's books in one of the schools in the city. Even the children would tease him if he liked anyone to be his girlfriend. He'd laugh at their curiosity. Court lady Ok-Nam insisted that the King should be dating someone and he is in his right age, but King Gon dismissed the thought of it.
He saw a person wearing a black hood that looked like the "white rabbit" in his description. He ran after the person while riding with his white horse. His quest led him to the bamboo forest, and suddenly, he heard the sound of the lightning and the music of the bamboo flute.
King Gon, all this time, has been holding the other half of the magical flute embedded in his small cane. Holding the mystic flute creates a power that lets him access to the different realm.
The Republic of Korea, the present time
King Gon was riding his white horse and soon enough, he landed on the streets of Seoul. The people who saw King Gon were attracted to his handsome face. They thought that he was an actor and filming a movie, with his outfit and the matching horse.
Detective Jung Tae-Eul (Kim Go-Eun) apprehended him for public disturbance. King Gon, however, was amazed by seeing her face. Detective Jung Tae-Eul has the same face on the ID he kept for 25 years. He tried to persuade Tae-Eul but she wasn't easily convinced. He then hugged her tightly. He was happy to see his savior.