Chinese secret agent Da-hee receives intel that a large number of illegal firearms are being smuggled into Korea and is sent to investigate the case. She meets Su-han, who is supposed to help her with the case, but due to his lackluster skills they fight over trivial things. But as their witnesses are suddenly murdered, the two of them quickly become the prime suspects.

A debt collector who looks intimidating, but actually has a warm heart, ends up becoming the guardian of a child, who has been left behind as collateral by her illegal immigrant mother.

Tae-bong, an informant in a smuggling operation, gets exposed during his mission. Meanwhile, bumbling detective Nam-hyuk stumbles into the chaos while attempting his own scheme. Forced into an uneasy alliance, the two must recover their losses and take down the criminals.

Even in the harshest environments, firefighters must focus on extinguishing fires and rescuing everyone there. At 3:47 AM on March 4, 2001, the 119 emergency call center receives a phone call about a fire that has broken out in the Hongje-dong neighborhood. Firefighters, including newcomer Cheol-woong, rush to the scene.