Do Ki seals the end of the painful vengeance against his mother';;;;s killer, but the wounds remain. The whistling that reminds him of his mother';;;;s last moment still lingers around his ears. Ha Joon newly joins Rainbow Transport as a troublemaker taxi driver, and he holds Do Ki as his role model. Ha Joon accidentally finds a secret passage that leads to the underground maintenance room. What is this place for? How will Do Ki';;;;s vengeful jouey for the victims unfold along with the precious people around him?