Hae Il is a priest in a small town. He takes care of problems in the neighbourhood, but things always get physical. He gets arrested while trying to stop a fraud. He has to leave the neighbourhood to avoid accusation. Meanwhile, Kyeong Seon who is a prosecutor, is trying her best to make connection with her seniors.

Hae Il leaves Yeosu and head to Gudam. He stays at the Catholic church of Father Lee Young Jun who is like a real father to him. Dae Young is a detective at Gudam Police Station. He goes out to support a local event, and protestors appear at the scene. Meanwhile, Hae Il walks by the scene and witnesses protestors getting beaten up.

Hae Il helps out the protestors at the ceremony and confronts Cheol Bum. Kyeong Seon gets a bribe from the accused of her case. New recruit Seung Ah joins Dae Young's team and becomes his partner. Meanwhile, Jang Ryong and his men make a scene at the church.

Jan Ryong and his men are released without any penalty. Father Lee gets a call in the middle of the night. Next day, he is found dead at a mountain nearby. Hae Il requests an investigation, but the Gudam Police and the prosecutor refuse. Police announce that Father Lee was involved in various crimes, and Hae Il gets furious.

Father Michael Kim Haeil returns, ready to take down a notorious and powerful drug cartel in Busan.

Haeil takes up teaching at a seminary in Busan, as drug lord Kim Hongsik arrives in the city.

Haeil digs into the cartel, while Hongsik begins building his empire in Busan.

Hae-il and Dae-young rescue Ja-young, while a suspect in interrogation suffers an accident amid the chaos, and the three decide to team up in their pursuit of the drug cartel; with his drug plant operational, Hong-sik begins expanding his reach.

Haeil and Hongsik sense the tension as strong rivals, while Kyungsun gains Duhun's favor.

Haeil's pressure on Hongsik and the cartel grows, leading Hongsik to plot a fierce counterstrike.

When the Virgin Mary statue is set ablaze, Haeil is certain it is the work of the drug cartel.

Haeil discovers Hongsik's true identity, leading to an intense face-off between the two.

Haeil's fall signals a new resolve. His team unites, prepared to crush the forces of darkness.

Under flawless disguise, Haeil and Kyungsun infiltrate the ship, but Kyungsun faces danger.

Haeil and Kyungsun narrowly escape danger, while Duhun and Hongsik each plot their own survival