In the corner of the city, a seemingly ordinary taxi company hides unknown secrets.When Nam Kyu, the murderer involved in the case, committed suicide in the training center, he had no intention of repenting, but instead left deeper doubts in Jiang Ha Nai's heart.Kim Do-ki, the core figure of the taxi company, seems to be inextricably linked to Zhang Shengzhe's case.

Jiang Hainai's intuition told him that there must be something fishy behind Jin Doji's unusual behavior.Through in-depth investigation, he found that the employees of this taxi company had very special backgrounds, and most of them had criminal records.Although the identities of these employees are complicated, Jiang Hanai firmly believes that there must be a connection between them and Zhang Shengzhe's case.

With the support of Deputy Chief Zhao, Jiang Henai obtained permission to search Zhang Shengzhe's home.However, Jin Doji learned the news in advance and took quick action to close the mechanisms and equipment leading to the secret room.When Kang Ha Nai and his party entered the room, they found nothing.The first confrontation between Kim Do-ki and Kang Ha-nae also started at this moment.

Kang Ha Nai firmly believes that no matter what the victims have experienced, it cannot be an excuse to challenge the bottom line of the law.He directly exposed Jin Doji's true thoughts and ridiculed him for satisfying his own hatred in the name of avenging others.However, Jin Douji did not retreat, but strengthened his belief.

During the investigation of the case, Jiang Hainai gradually learned about the background of the victim Gao Tongyi.Gao Tong Yiyin got acquainted with his well-connected girlfriend Li Huiyan and received help in his career.However, after a business meeting and a drinking party, he mysteriously disappeared.Police eventually found his body in a suburban warehouse.

When Jin Doji took the photo of the murderer from Father Gao, he was surprised to find that the murderer was Baek Romi's secretary Goo Seok-tae.However, Father Gao unexpectedly gave up the idea of ​​revenge.The decision saddened the team members because they could no longer take on the case.

At the same time, Kang Ha Nai found the real suspect Gu Yingtai based on the file.He is Gu Seok-tae's twin brother, but because of his similarity in appearance, Kim Do-ki and Jang Sang-cheol previously mistakenly identified him as the murderer.Gu Yingtai is the president of a company. He is arrogant and domineering and regards the law as nothing.

Kang Ha Nai's application for extended detention was rejected because there was no clear evidence to overturn the previous investigation.However, he didn't give up.He decided to start with Gu Yingtai's subordinate Shen Youxie and let him become his informant.Shim Woo-seop was hesitant at first, but considering how humiliated Goo Young-tae had been to him, he finally agreed to help Kang Ha-nae.During a drinking session, Shen Youxie deliberately got Gu Yingtai drunk and obtained clues about his murder and body hiding.