Do-ki goes into Jangsan Correctional as an undercover inmate. He fights all the way through every trap that Ha-joon has prepared for him. Although he barely makes it in one piece, he saves Lee Si-wan. Meanwhile, Ha-joon learns about his true identity and what the Bishop has done to him since his childhood.

Rainbow Transport takes in another client. However this time, it is a set-up made by the Bishop and Ha-joon. Not knowing that it is a trap, Do-ki blindly goes into Jangsan Correctional with Kyung-goo and Jin-eon to save a victim. The only thing that is waiting for him is Ha-joon's trap that will break Do-ki into pieces.

Rainbow Transport officially begins its operation to bring punishment to Sang-gi. The plan mainly depends on Sung-cheol being a loaded old man as bait. As soon as Sang-gi sees this and plans to scam him, he does not realize the karma that he is about to face. Meanwhile, the secret organization Do-ki is after is also keeping an eye on Do-ki as well.

While Do-ki wakes up from getting drugged, the bishop comes back to Korea. Now that Do-ki has evidence of how Black Sun is circulating drugs, he sets up a plan. Meanwhile, Ha-joon notices that Rainbow Transport is on Black Sun’s tail. Knowing how skillful Do-ki is, he takes every precaution he can take.

After Do-ki gets kicked out from Black Sun and gets beaten up, the police arrive. However, the police arrest Do-ki instead. Although Yong-min helps him to bail out, Do-ki now knows that the police are working with Black Sun. Rainbow Transport infiltrates the club to take them down for all the crimes they are committing.

Do-ki becomes a patient himself to infiltrate the operating room. When he is put to sleep, Go-eun finds out that there is a proxy who does the actual surgery while Young-sook goes somewhere else for a drink. Now that the team knows she is a complete fraud, they set up a meticulous plan to bring the witch down.

Do-ki successfully infiltrates Cheongeum with the help of his old crew. He pretends to be an abducted recruit but secretly searches for Dong-jae. During the search, he runs into Lim Bok-ja. He uses her revengeful anger to make it easier to find the missing boy. Just when he is about to capture the mastermind, a mysterious gun shot interrupts his arrest.

The team pulls together for one final mission to nail the true culprit behind the death of Do-gi's mother. Ha-na attempts to resign.

Do-ki runs into a stray little girl on the street. Out of concern, he takes her to Rainbow Transport and learns that suspicious people are after her. Do-ki and the team tries to infiltrate Feel Consulting and get some info on Kang Pil-seung to find out why he is in search of this poor little girl.

Do-ki and Go-eun get busted by Pil-seung for putting up an act. However, Do-ki manages to win back his trust by acting how desperate he is for a house. Now that they are back on track, Do-ki learns how Pil-seung is able to help couples get housing by using children. Disgusted by his ways, the team is determined to bring down Pil-seung at all costs.

When Yeong-mi comes after the team, Do-gi throws himself into action to save them from her cruel clutches before it's too late.

To catch the used-car dealer gang, Do-ki begins aggressively buying up their used cars. Becoming suspicious, the gang follows him after seeing that he even brings in a car carrier to purchase the vehicles. Falling into a trap Do-ki has set, they ultimately end up signing a malicious contract — just as they once forced their victims to do.

Shaken by an abusive experience, a young woman with an intellectual disability takes up the services of Kim Do-gi and his team of revenge seekers.

Do-ki’s plan to meet the boss of the yakuza seems successful. He gains Matsuda’s trust in his own way and gets closer to the crimes they’ve been committing. However, an unexpected group of people appears. It turns out that the Interpol is also looking into this human trafficking case. Michael, the Interpol inspector, wants Do-ki to support the investigation, but Do-ki has his own goals.

Do-gi goes undercover as a high school substitute teacher after receiving a call for help from a student who is being severely bullied.

To gain access to Park Yang-jin's inner circle, Do-gi focuses his efforts on infiltrating a key department within the company.

With an eye on payback, Do-gi transforms into a deep-pocketed customer to trick Kang Maria's tormentors. Kang Ha-na wonders about a missing criminal.

Ha-na grows suspicious when she finds Do-gi's ID card at the scene of the explosion. Meanwhile, the team takes on a phone scam case.

While Ha-na looks into allegations of employees suffering physical abuse inside a powerful tech company, Do-gi poses as a new recruit there.

A call brings the team together again. A girl named I-seo calls for help, but she disappears as soon as Sung-cheol answers. The investigation begins with only a name, but the team discovers that there’s a scam game that lures teenagers, and there’s a Japanese loan company behind it. To find I-seo, the team goes to Japan.

A bolt-from-the-blue piece of news strikes Driver Oh, who had been preparing to operate his own private taxi. The Taxi Driver License he had hurriedly obtained ends up holding him back. When Rainbow Taxi discovers that there are serious issues with Driver Oh’s previously stolen Taxi Driver License, everyone steps up to help. Will they be able to catch the illegally operated car dealer?

The team is taken by surprise when Baek Yeong-mi empties the secret prison cells. Do-gi plans to use Gu Yeong-tae as a bargaining chip.