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.

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.

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

The three bullies' attempts to mess with Do-gi come to a halt when they realize he possesses video footage that could ruin their lives.

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

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

As the truth behind an exploitative incident involving An Go-eun's sister comes to light, Do-gi sets out for revenge. Ha-na shows up with a warrant.

Do-gi finds himself in danger after Yang-jin gives him a cruel test of loyalty. Go-eun returns to locate and destroy the data servers.

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.

Do-gi dons another disguise to lay his charms on the leader of the voice phishing operation. Ha-na keeps a close eye on the team's whereabouts.

Certain that Jang Seong-cheol and his employees are hiding something, Ha-na storms his home. A pastor worries about his missing son.

In mourning, Ha-na goes to Do-gi as a client in search of vengeance. While investigating, the team uncovers a larger scheme at play.

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.

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.

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.

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.

Despite the disbandment of Rainbow Taxi, Do-ki is still out there going after bad guys. While keeping it from the rest of the members, Do-ki and Sung-cheol secretly help out a father who is searching for his missing son. To confirm his whereabouts, Do-ki sets off abroad to a foreign country to accomplish his first mission.

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.

An elderly woman visits Rainbow Transport as a victim. She owes a lot of money because of a young scammer who only rips money off old people. Do-ki and the team get infuriated upon seeing this and set up a plan to prevent this criminal from ever scamming the elderly again.

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.

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.

The next client is a woman named Lee Jin-hee. Her beloved sister Jin-sun is suffering from a terminal disease and is relying on a cult to cure her. To save her from the cult and to take down its leader, Rainbow Transport begins service. However, Do-ki is not the one who will be infiltrating the cult this time.

The plan to destroy Ok Ju-man is now set. The only thing that remains is for Ju-man to take the bait. Although he does not have faith in any kind of religion, the Rainbow Transport team makes it seem believable. By setting the perfect scam, Ok Ju-man becomes faithful to the fake cult that Do-ki makes.

A smelly drunk man protests alone in front of a big hospital. He claims that his daughter is in a coma due to a surgery malpractice. Although Rainbow Transport took him in as a client, they are not sure whether this is an actual case or just an accident. Before they start anything, Do-ki looks into Ahn Young-sook, the director who performed the surgery.

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 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.

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.

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.

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.

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.

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.

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.

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.

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?

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.

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.

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.

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.

A fire breaks out at Im Dong Hyeon's gym, and he's found dead at the scene. Jo Seong Uk is also found drowned. The van transporting Min Ho's body is hit by a car, and the body is stolen. Do Gi and the team figure out that there's a man behind all three incidents, and they finally encounter him.