For Ho-yeol, a cleaner who escaped a world out of control, the bathroom is a 'sanctuary' free of any speck of dust. However, the sanctuary instantly turns into a crime scene due to an uninvited guest's intrusion and an unexpected accident caused by his obsession. To make matters worse, in an extreme situation of a water outage, Ho-yeol begins a frantic struggle without a drop of water to erase a 'giant stain.' After the holy war ends, can he return to his daily life? Or is there something left that he must control for the last time?