Set in the 1980s, a husband and wife, both detectives, infiltrate a massive criminal organization responsible for the illegal drug trade between Korea, China, and Japan.
Episode 1
Detective Joon-mo goes undercover within Gangnam Union to probe an international drug trade.
Episode 2
Barely passing Ki-cheol's test, Joon-mo joins Gangnam Union and discovers an unexpected truth.
Episode 3
Eui-jung's appearance puts the squad in trouble. Ki-cheol finds last night's attack suspicious.
Episode 4
The team seeks Eui-jung's aid to assist Joon-Mo in a crisis, which leads to a perilous love triangle.
Episode 5
Earning Gi Cheul's trust, Jun Mo becomes anxious as he sees Gi Cheul making a move towards Eui Jeong.
Episode 6
The delivery accident has put the trade on risk, While Detective Hwang closely monitors the Gangnam union.
Episode 7
Hae-Ryeon shows interest in Joon-mo; Eli-Jung approaches Ki-cheol; Joon-mo takes an extreme measure.
Episode 8
Ki-check suspects Joon-mo. The four people's irreversible decisions trigger the biggest crisis.
Episode 9
The battle with Jaegeon creates a crack. Joon-mo joins forces with Hae-ryeon to resume the trade.
Episode 10
Joon-mo and Eli-Jung juggle duty and feelings. Hwang continues to meddle, and the final day arrives.
Episode 11
An accident halts the trade and a crisis approaches as Eui-jung and Dohyung worry about Joon-mo.
Episode 12
Ki-cheol and Joon-mo make their way to the final deal. Korea, China, and Japan prepare for the arrest.
