Crash

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.

TCI’s investigation into ghostly apparitions causing vehicular accidents uncovers a multiparty Car Scam Ring affiliation. So-hee’s father, Min Yong-gun (Yoo Seung-mok), shares some of her background story with Yeon-ho. Yeon-ho and So-hee go undercover as husband and wife.

The TCI investigates the case of a woman jumping from a car. The Joint Investigative Unit moves to Namgang Police Station and takes over TCI’s case. Cha Yeon-ho is disgraced when a culprit gets away. So-hee decides to give him personal training in the finer arts of police arrest techniques.

The Hit and Run Case sheds light on a Car Thief and Serial Rapist case. Mysterious envelopes related to Cha Yeon-ho’s tragic past traffic accident appears. Min So-hee may be a little over zealous in the police arrest techniques training. Yeon-ho confronts Deputy Commissioner Pyo Myung-hak (Heo Jung-do) who investigated his case in the past.

Cha Yeon-ho is interrogated in regards to his past vehicular homicide case. When Director General Lee Tae-joo (Oh Eui-sik) of the Joint Task Unit withholds information from his team and the TCI, they go to the aid of TCI.

Pyo Myung-hak is promoted to Commissioner General. TCI’s investigation into a car carrier trailer rollover case finds that it was malicious and caused the death of a man driving home. Yang Jae-young (Heo Ji-won), the son of a former gangster, is murdered. Eo Hyeon-gyeong (Choi Moon-hee) meets Woo Dong-gi’s (Lee Ho-cheol’s) father, Woo Gil-soon (Joo Hyun).

TCI reveals a serial pattern in the Car Carrier Trailers Rollover Case which affected prior truck drivers for CY Logistics. Woo Gil-soon was one of them. Truck driver Han Kyung-soo (Han Sang-jo) confides the names of the individuals related to Cha’s past accident and that all had received threatening mail.

TCI is assigned the Yang Jae-young Murder Case. Min Yong-gun (Yoo Seung-mok), So-hee’s father, gets involved in an accident while chasing a Hit and Run driver. Evidence leads to Pyo Jung-wook (Kang Ki-doong), the Commissioner General’s son. Yeon-ho shares his knowledge of his accident from 10 years prior with So-hee.

Cha Yeon-ho finds out that Kim Hyun-min (Kim Dae-ho), the National Forensic Service analyst is the culprit behind the threatening envelopes. Pyo Jung-wook seeks the help of former gangster Yang Seok-chang (Lee Yoo-joon), Chairman of YSC Group. Han Kyung-soo confesses who the actual culprits were in Yeon-ho's vehicular homicide case.

TCI succeeds in capturing the real culprits of the 10 year vehicular homicide, car carrier and the Hit and Run cases. During Pyo Jung-wook’s trial, Commissioner Pyo is also implicated and arrested. Conniving Lee Tae-joo is promoted to Chief Superintendent. Rather than being promoted the team is dissolved and transferred. Cha Yeon-ho is sent to remote Hwapyeong island.