Besides offering rides to passengers, a group of employees at Rainbow Taxi also discreetly offers a special revenge for hire service. Kim Do-Ki (Lee Je-Hoon) leads the revenge group with Owner Jang Sung-Chul (Kim Eui-Sung), Hacker Ahn Go-Eun (Pyo Ye-Jin), Mechanic Choi Kyung-Koo (Jang Hyuk-Jin), and Mechanic Park Jin-Eon (Bae Yoo-Ram). People that have been victimized and cannot find redress through normal channels, reach out to Kim Do-Ki's group to finally receive justice.
After finishing their last mission, some members of the revenge team at Rainbow Taxi decide to go their separate ways. Kim Do-Ki remains at Rainbow Taxi with Jang Sung-Chul, but the others take on new jobs and careers. Now, 2 years later, Kim Do-Ki travels to Vietnam to help a father find his missing son, who went there for employment. As the case becomes more complicated and dangerous, Ahn Go-Eun, Choi Kyung-Koo, and Park Jin-Eon decide to return to Rainbow Taxi to do what they do best. Rainbow Taxi also has hires new employee On Ha-Joon (Shin Jae-Ha).