A man referred to simply as the "Postal Dude" has been evicted from his home. He believes the United States Air Force is releasing an airborne agent upon his town of Paradise and that he is the only individual unaffected by the ensuing "hate plague". He fights his way from his house to an Air Force Base through various locations, including a ghetto, train station, trailer park, truck stop, and an ostrich farm. During the course of the gameplay, a voice in the protagonist's head (voiced by Rick Hunter) can be heard taunting his victims through cryptic absurdity, often through consecutive kills or when switching through the player's arsenal.
After raiding the Air Force Base, he is shown attempting to massacre an elementary school. Despite his best efforts, his weapons have no effect on the children. Suffering a mental breakdown amidst innocent laughter, he finds himself restrained in a mental asylum as hellish images cover the screen: A body bound to chains in a corridor, the protagonist in a straitjacket curled in the fetal position; a close-up of his face (albeit covered by bindings) and the door to his cell numbered 593. A disembodied voice, possibly a psychologist, gives a report on the protagonist's mental state: He suggests that the stress of urban life may have been the root cause of his rampage, prompting him to "go postal". The lack of any mentions of military interference with the civilian population strongly implies that the Postal Dude's murders were the result of his own paranoid delusions. Amid distorted audio, the psychologist gives a final remark: "We may never know exactly what set him off, but rest assured we will have plenty of time to study him". Upon completion of the credits, manic cackling can be heard as the screen fades to black. It is suggested that the protagonist may have escaped the confines of the asylum to pursue further acts of violence.
Due to the controversy surrounding the game's release, along with numerous, unrelated American school shootings in the years following, the 2016 redux of the game's ending has been changed. Replacing the elementary school vision is the player witnessing the burial of an unknown person in a decaying field, though it can be implied that it is his own. Completion of the game on the hardest difficulty features the inclusion of an unknown male and female mourning over the grave as it descends. Both outcomes prompt a similar mental breakdown and an identical asylum cutscene, though consisting of animated shots over the original release's still image artwork
