In an unjust society, one phone call to Rainbow Taxi will summon the taxi driver Kim Do-ki to avenge you. Do-ki is a guy who has lived more honestly than anyone as an officer in the Special Forces. But when his mother is murdered by a serial killer, he spends his days in agony. While feeling wronged and broken, Do-ki meets Jang Sung-cheol who recruits Do-ki to work for his company, Rainbow Taxi. Far from an ordinary taxi service, Rainbow Taxi is a secret organization that avenges victims who were not protected by the law. Here, Do-ki becomes a star driver who delivers satisfying revenge. Meanwhile, Ha-na is a prosecutor who investigates Rainbow Taxi. She is furious with their lawless behavior, but at the same time, she feels confused to see them solve cases that the law cannot. Between those who believe that revenge embodies true justice and those who pursue the outlaws, Do-ki seeks what justice truly means.
