The story starts in 1983. The South Korean president and his delegates are visiting Burma (now Myanmar) when a bomb planted by North Korea explodes, killing some high ranking officials. This historical event is called the Rangoon bombing (also known as the Rangoon incident). To strike back, five South Korean officials plan an underground operation to enter North Korea and kill North Korean agents. Unbeknownst to the South Korean president, Lee Jin Pyo (Kim Sang-joong) and Park Moo Yul (Park Sang-min), two bodyguards at the Blue House (South Korean presidential palace), organize a 21-men troop to execute the plan. However, as the operation is taking place, five high-ranking officials change their minds and abort the plan in order to avoid an international crisis if the mission is discovered. Their major concern is that the United States will withdraw its nuclear protection if the mission is made public.
The operation is successful, but as the troops swim to the submarine which is supposed to take them back to South Korea, snipers from the submarine shoot and kill all of the troop members, except Lee Jin Pyo, while they are still in the water. An already injured Park Moo Yul uses his body to shield Jin Pyo, thus saving his life. Jin Pyo swims back to shore and returns to South Korea, where he finds out that there are a total of five officials responsible for aborting the operation.
Vowing to avenge his fallen comrades, including his closest and best friend Park Moo Yul, he kidnaps Moo Yul’s infant son and flees to Southeast Asia’s Golden Triangle, specifically the mountainous Burmese-Thai border. There, he raises the child as his own and trains the boy intensively in combat. Following an attack on the village, Jin Pyo confesses his long-term plan for revenge to the child, Lee Yoon Sung (Lee Min-ho).
Seven years later, after successfully finishing his college years and attaining a doctorate in the United States at the Massachusetts Institute of Technology, Yoon-sung returns to South Korea to fulfill his step-father’s plan for revenge. He enters the Blue House as an IT expert under the National Communication Network Team. He is warned by Jin-pyo not to trust anyone and never to fall in love, as doing so will put the people around him in danger.
In Blue House, he meets bodyguard Kim Na Na (Park Min-young). The story of love and revenge begins. Eventually Kim Na Na helps him to take revenge, as they discover that they have the same goal in mind. Both of them start working together, but problems occur during their revenge plot.
A twist occurs as the full truth is revealed.
Lee Min Ho as Lee Yoon Sung/Johnny Lee / Poo Chai
Lee Yoon Sung is the “City Hunter”. His ultimate goal is to avenge his father’s killers as the City Hunter. Using the dead Korean-American John Lee’s identity, he gets his Doctoral degree at MIT, and enters employment at Korea’s presidential palace. While taking revenge, he falls in love with a presidential guard called Kim Na Na. He tries to protect Na Na from the many enemies hunting him down.
Park Min Young as Kim Na Na
She is a judo master, forced to fend for herself at an early age after her mother was killed in a drunk driving accident and her father was placed in a coma. She has to take many jobs in order to support herself. Her exceptional skills in martial arts allowed her to be chosen as one of the president’s bodyguards. During her time as a bodyguard, she falls in love with Lee Yoon Sung. Unknowningly shooting him in the shoulder while he was city hunter, she later discovers his identity and tries to aid him in his revenge.
Lee Joon Hyuk as Kim Young Joo
An intelligent prosecutor, Kim Young Joo possesses a strong sense of justice, even against the corrupt politicians of South Korea. He is Jin Sae Hee’s ex-husband as well as the son of one of the officials that ordered the slaughter in 1983. He is constant rival of the City Hunter, working towards the same goals, but wanting to do so within the context of the law rather than outside it.
Kim Sang Joong as Lee Jin Pyo
The only survivor of the slaughter 28 years ago. Full of anger, he wants to kill all of the people who ordered the execution. He pretends to be an investor from America and starts his revenge through his dead best friend’s son, Lee Yoon Sung.
Kim Sang Ho as Bae Shik Joong
A gambler who is saved by Lee Yoon Sung from thugs in Thailand and later becomes his close friend. It is Bae Shik Joong who asks Lee Yoon Sung to look after Kim Na Na when he is sent to South Korea, and joins him there later to assist him in his mission.
Hwang Sun Hee as Jin Sae Hee
Kim Young Joo’s ex-wife and good friend, a veterinarian.
Goo Hara as Choi Da Hye
The president’s academically challenged daughter, who begins with a crush on Lee Yoon Sung, but switches over to liking Kim Young Joo.
Chun Ho Jin as Choi Eung Chan
The current president of South Korea. He was one of the five men involved in the event of 1983. He swore to the men going into North Korea that he would get them back out, but was later out-voted and forced to live with the guilt for 28 years. He is the only member of the group who is aware of the survival of Lee Jin Pyo, yet does nothing to stop him despite knowing that Lee Jin Pyo’s ultimate goal is to end Choi Eung Chan’s life.
Park Sang Min as Park Moo Yul (Andrew)
Kim Mi Sook as Lee Kyung Hee (Susan)
Lee Seung Hyung as Song Young Duk
Yang Jin Sung as Shin Eun Ah
Lee Kwang Soo as Go Ki Joon
Kim Byung Choon as Jang Woo Hyun
Shin Young Jin as Kim Mi Ok
Lee Hyo Jung as Lee Kyung Wan
Choi Jung Woo as Chun Jae Man
Choi Il Hwa as Kim Jong Shik
Choi Sang Hoon as Seo Yong Hak
chae sang woo as child Poo Chai