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.

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.

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.

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.

It's the end of the road for Seong-cheol and the team as they agree to shut down their operation. Do-gi is made to face the demons of his past.

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.

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.

Do-ki makes it out alive from the car bomb explosion. He uses his death to track down the person behind the vicious attack. While his funeral progresses, Do-ki and the team monitor any suspicious people coming and going, which leads them to a club for the rich in Gangnam. Do-ki makes his entrance to find out more.

An angry VIP client at Black Sun puts the security team on edge. The security team gets a second chance to make another delivery. Only this time, Do-ki joins the team. What he learns is shocking. Meanwhile, Sung-cheol digs into Ha-joon's past.

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 Gi and his group infiltrate the island and encounter a series of unexpected situations. Jin Eon and Gyeong Gu, who were tailing Writer Go, find themselves in danger, and even Go Eun, who was chasing the fish truck driver, ends up in peril. Realising that all of his teammates are in danger, Do Gi ultimately joins their scheme to rescue his comrades.

Do Gi and his crew find out the entire criminal history of the Samheung Island criminal ring. Do Gi's crew sees how they don't even hesitate to kill people to achieve what they want, so they come up with a plan to break up the organisation. However, Do Gi falls into danger after the criminals find out what they are after.

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.

Dong Su was on the verge of giving up his life 15 years ago when he first met Mr. Jang. To right the injustice done to Min Ho, his son, Dong Su tried everything but failed. Mr. Jang helped him with all his might, but Dong Su just disappeared one day. Hearing the story, the Rainbow Deluxe Taxi takes on the case and starts digging into the old case.

While driving the Deluxe Taxi, Do Gi rescues Ro Mi, an idol trainee who jumped into the Han River. Ro Mi is facing a crisis where her debut could be cancelled because of the trap her managers put her in. After hearing Ro Mi's story, the Rainbow Taxi members infiltrate her agency, Yellowstar, to uncover the full circumstances.

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.

Chief Choi tries to help Maria’s sister, Da Som, on his own, but he ends up getting scammed instead. The Rainbow Transport members learn about Yoo Min Jung, who was scammed like how Chief Choi was through a resale app. Do Gi figures out there’s a whole organization behind it.

Do Gi and Chief Choi sneak into the gambling den to see what Im Dong Hyeon is up to. Do Gi even manage to take over Im Dong Hyeon's gym through gambling. Meanwhile, Dong Su passes out after attempting to harm himself, and Mr. Jang finds mysterious codes next to the bed.

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?

On the day of Elements' debut, Ji An passes out, so Do Gi covers for her during the rehearsal. After seeing Do Gi's good performance, CEO Kang Ju Ri gives him more trust, and she even shares her dark past. Do Gi then figures out that CEO Kang is using the trainees to entertain her clients, instead of making them real idol singers.

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.

After learning that the gym was being used to fix volleyball matches, Do Gi returns it to Im Dong Hyeon for a bigger plan. He pretends to be a big-shot agent from Europe to win over Jeong Yeon Tae, a player who rigged matches for Im Dong Hyeon and Jo Seong Uk. On the day of the finals, Do Gi delivers the final blow that will help him find the body of Park Min Ho.

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

Upon hearing the news that Master Sergeant Yoo Sun A, with whom he had served, has died, Do Gi immediately heads to the military unit where Master Sergeant Yoo last served. Before she died, she was demoted three ranks, which is unusual. Do Gi seeks to uncover the truth behind her death by following the last mission she carried out before she died.