Jung Gicheul rises from a nightclub DJ to a crime boss in the span of two years, and starts a far-reaching drug trade.

Park Junmo is approached to begin a dangerous undercover operation to take him down.

There's a pitched battle in the hallway of the Gangman Union's headquarters. Park Junmo shows up, in a white suit, just in time to see Yu Euijeong. He begins to fight his way toward her as she's dragged off by an attacker... covered in blood, he pauses, dazed, in the midst of the battle...

2 YEARS AGO, 1994, SEOUL, SOUTH KOREA

It's a beautiful summer day when husband and wife Park Junmo and Yu Euijeong get in the car. Yu Euijeong is transferring to the security division today. Later, at dinner time in her parents house, Euijeong's father and brothers insult Park Junmo for being a mere low-ranking detective, and also insult Junmo's father. Euijeong's mother is not at dinner, as she's sick in the hospital. Disheartened, Junmo goes into Euijeong's old room where his wife joins him eventually. Junmo finds a cross necklace in her jewelry box that Euijeong reveals is from her church back in high school.

GANGNAM, SOUTH KOREA

Choi Jungbae and others ride around promoting the nightclub Jung Gicheul works at as a DJ. In a back room, Sergeant Jang Kyungchul asks Jung Gicheul to join his gang and bring his friends with him in return for a nightclub of his own. Gicheul takes the bargain.

1 YEAR LATER, 1995, GANGNAM, SOUTH KOREA

Gicheul is dressed dapperly, striding through the city to meet with someone sitting in an idling car who recommends a Professor Yoon. Choi Jungbae calls Gicheul into the nightclub where there's an incident with a rich man trying to take advantage of Mijin, one of their hostesses. Gicheul wants to fight him, but Mijin stops him from doing so since she knows that the client is rich and it could get them in trouble. Gicheul's attempt at breaking up the altercation ends pathetically, and the rich man throws money at Gicheul before going back to forcing himself on Mijin. Later, for his attempt at a good deed, Gicheul is threatened by Hando, a member of Sergeant Jang's gang.

In the sauna, Gicheul approaches Sergeant Jang with an idea to consolidate the drug trade, which Sergeant Jang doesn't appreciate.

In an eatery, Jung Gicheul, Kwon Taeho, Choi Jungbae, and Hong Heesung sit around disconsolately. Gicheul wants more than this life, and his friends swear that they'll follow him in whatever move he decides to make.

In an underground car park, Gicheul waits on the stairs as Mijin cajoles the rich man who has the hots for her into the car. The man is exceedingly drunk. Once Mijin leaves, Gicheul beats the man up violently and leaves him bleeding in the car.

Gicheul approaches Lee Hyangjin and gives him meth in exchange for private access to an exclusive hotel in Jeongseon. Gicheul approaches the "knife-wielder" Seo Jongryul, who has killed a man and served 5 years already, with an offer to join his gang in exchange for owning two clubs in Gangnam.

NEW JEONGSEON HOTEL

Gicheul and his friends as well as Sergeant Jang's gang take a vacation in an exclusive hotel with no other guests. Later that night, Gicheul holds the cross necklace around his neck and considers using his gun before putting it away in a drawer. In black leather jackets, Gicheul and his gang invite Chief Seo and his men into the hotel. Both combined forces join in pitched battle, wielding metal baseball bats, against Sergeant Jang's gang.

Gicheul's forces are winning when he and Taeho chase Sergeant Jang into the abandoned dining room, where Sergeant Jang finally surrenders. Chief Seo offers to kill Sergeant Jang, but Gicheul wants to have Sergeant Jang arrested instead, so Taeho puts him in handcuffs. However, while he is doing so, Taeho becomes enamoured by the watch on Sergeant Jang's wrist. Taeho steals the watch, but Sergeant Jang, enraged, stabs him with scissors.

Horrified, Gicheul watches his best friend die and then stabs Sergeant Jang a number of times in retaliation using Chief Seo's knife, committing what is presumably his first kill.

BUSAN, SOUTH KOREA

Gicheul approaches Song Donghyuk with the information that Sergeant Jang has "disappeared" after deciding to cut ties with Busan. He shows Song Donghyuk photo evidence of Sergeant Jang standing with Jaegeon Group's Sung Kisoo. Song Donghyuk considers having Gicheul killed, but Gicheul offers to work under him and send him 50 million won each month.

Gicheul approaches Professor Yoon, revealing that he is the one who had sent her a travel brochure to China. Professor Yoon mentions that he'd given her a gold watch along with the brochure.

In one of Gicheul's nightclubs, Mijin takes drugs and falls to her death from a balcony.

SEOUL CENTRAL DISTRICT PROSECUTOR'S OFFICE

Cho Changsik, Chief Prosecutor of the Serious Crime Division, meets with Murayama Hideaki of the Tokyo Metropolitan Police Narcotics Control Department. They discuss a large-scale trade in meth with Japan that seems to be coordinated by a Korean gang, and decide that an undercover operation, in which they catch evidence of the trafficking at the scene, will be necessary to stop it.

EUEMSEONG, SOUTH KOREA

Seok Dohyung meets with his old friend, Park Junmo, to offer him the undercover job. Junmo refuses, but Dohyung brings up Junmo's father as a reason for him to be worried about meth becoming more widely available. Later, Cho Changsik approaches Junmo, mentioning that everyone knows about the scene Junmo's father made at his wedding, and reveals that no one will ever promote a drug addict's son—but an exception might be made if he takes this mission.

Seok Dohyung leads Park Junmo to the conspirator's HQ, a room hidden in a rundown part of the city. Junmo takes the mission on the condition that he'll be moved up two ranks, rather than just one. Junmo goes over the basics of the case and is introduced to his cover as a man named Kwon Seungho, Taeho's cousin who had worked on a fishing boat. Junmo decides to come up with his own way to meet Gicheul, at the restaraunt Sikgaek in Yeoksam-dong. Junmo sits down at a table and refuses to order, asking for Jung Gicheul by name and attacking everyone who tries to kick him out.

Jung Gicheul, Choi Jungbae, and Hong Heesung are driving on their way to the restaraunt when they hear about this. Choi Jungbae counsels against it, but Gicheul decides to meet the guy who's going to such lengths to get his attention. He shows up at the restaraunt but is soon shocked by the sight of Taeho's watch on Junmo's wrist.