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.
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.
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.
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 finds the mastermind behind the resale app scheme, but the scammer gets killed by a bomb delivered by a guy in a fish truck. Do Gi and Mr. Jang trace the fish truck, which leads them to Samheung Island. The islanders seem unusually hostile toward Do Gi and Mr. Jang. Later, Do Gi finds out that the islanders have been watching their every move.
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.
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.
Do Gi finds the bird nest where the late Yoo Sun A left the intel and learns that she sacrificed her life to save her comrades. He also finds out that higher-ranking officers fabricated the special mission for their personal gains. To eliminate the problematic officers, Do Gi uses all the help he can get.
