Insurance Investigator Cha Yeon-ho (Lee Min-ki) is accidentally caught up by the Traffic Crime Investigation Team (TCI) during a "Car Fraud" gang bust. During questioning he shares his case records of a possible Vehicular Serial Murder case with Lieutenant Min So-hee (Kwak Sun-young). So-hee gets personally involved after she finds out an acquaintance may have been a victim.

Killer Jung Ho-kyu (Bae Yoo-ram) plots his revenge against Jo Seok-tae (Lee Do-goon) for aiding Lt. Min So-hee. Investigator Cha Yeon-ho obtains damaging evidence against Ho-kyu. Yeon-ho gets labeled as a whistle blower and quits his job. Capt. Jeong Chae-man (Heo Sung-tae) of TCI hires him into the team as a Lieutenant due to his investigative expertise.