National Tax Service is the tax organization responsible for taxation. Among the many bureaus and divisions, the 5th Taxation Bureau, nicknamed the 'dumping site,' handles the most notorious cases and thus scores the lowest success rate. That changes when Hwang Dong-joo gets transferred as one of the team leaders. Hwang, infamous as the nutjob, keeps closure on complex taxation cases. That draws much attention from inside and outside the organization, especially from those who know Hwang's history.