In the post-Apocalyptic American wasteland, eighteen-year-old Finn finds himself drifting down the Mississippi while hordes of human mutants roam the planet. He is heading to a colony of Doomsdayers to hook up with Margie87, who he's known for years, thanks to ham radio. But along the way, Finn meets up with Cat, a sarcastic little vixen who leads him on and steals his raft. He takes off after her, fights the raging hordes, abandons her on an island, then heads into a furious storm and is rescued by a mutant. But along comes Colonel Krunk, who abducts Finn and takes him to the colony, where they're holding human "dogsters" to trade for fuel. Finn confronts a mad scientist and finally finds Margie87. Chaos erupts and Finn escapes along with an unlikely gang of underdogs.