It all start with martial arts expert San (Lee Min-ho) and master sleuth Yo (Wallace Chung) who have been working as bodyguards-for-hire but to little success since their dismissal as Interpol officers a year ago. When a vague commission leads them to a hotel room in Incheon, South Korea, a terrorist bombing duly takes place and turns the bumbling investigators into wanted suspects. Their informant dies at the scene, but the pair also immediately find themselves pursued by a rival group of bounty hunters.