In 2017, the percentage of insurance purchase rate in Korea is 95%. There’s only 5% chance of meeting someone with no insurance plan. Choi Kang Woo is a former detective who works as a private investigator after having his wife and son badly hurt in an airplane accident. Jang Ha Ri used to be a gymnast, but she now works as an investigator for Mag Dog. One day, Kang Woo and Ha Ri run into Min Joon in the midst of a fraud crime investigation.

Two years ago, Kang Woo’s team was investigating on an insurance fraud case that involves a man named Ko Jin Chul. While chasing him down, the team’s newbie gets in a car accident, which causes Kang Woo to miss his flight to Jeju Island that he planned to go with his wife and son. The plane carrying Kang Woo’s wife and son crashes. The pilot responsible for the crash turns out to be Min Joon’s brother, Kim Bum Joon.

Min Joon threatens Kang Woo to get what he wants with a clip that contains all the illegal deeds Kang Woo committed while investigating cases. Kang Woo secretly goes into Min Joon's house where he finds the articles related to the plane accident posted up on the walls.

Kang Woo finds out that Min Joon is after Lee Mi Ran who made Bum Joon take out 8 different insurance policies before the plane accident. Kang Woo helps Min Joon by chasing Lee Soo Oh to find out why Kim Min Joon is after Lee Mi Ran, who's supposed to be dead.

Both Kang Woo and Min Joon go after Lee Mi Ran who is still alive. Min Joon steals Cheetah's phone to get information, and he finds Lee Mi Ran before Kang Woo does. Meanwhile, Hong Joo realizes there's a dark secret regarding the flight accident that's thought to be a suicidal crash.

Kang Woo doesn’t understand why Ko Jin Chul killed Lee Mi Ran and why he had to hurt Min Joon. Mad Dog members set a plan to catch Ko Jin Chul, and Min Joon moves on his own after he wakes up from the hospital.