Mad Dog

Choi Kang-woo, an ex-detective, forms his own investigation team after losing his family in a fatal aeroplane crash; Kang-woo encounters Min-joon while investigating a fraud case.

In the past, Kang-woo works to arrest Ko Jin-chul, an insurance fraudster and murderer; Kang-woo plans a trip to Jeju Island with his family but goes out to help a struggling new policeman; Kang-woo family dies in a plane crash.

Min-joon threatens Kang-woo with a clip containing all of Kang-woo's misconducts; Kang-woo breaks into Min-joon's house and finds something strange.

Kang-woo finds out that Min-joon is looking for Lee Mi-ran and joins him in pursuing the supposedly dead woman.

Kang-woo and Min-joon team up to catch Lee Mi-ran; Hong-joo discovers a sinister secret about the aeroplane accident.

Kang-woo tries to figure out why Jin-chul killed Mi-ran; the team plot to catch Jin-chul; Min-joon decides to capture Jin-chul on his own; Hyun-gi tells Jin-chul to kill Min-joon.