Agents of an oil tycoon vanish while exploring a swamp marked for drilling. The local sheriff investigates and faces a Seminole legend come to life: Man-Thing, a shambling swamp-monster whose touch burns those who feel fear.
Sheriff Kyle Williams comes to Bywater to replace the missing sheriff and he learns from his deputy Fraser that there are other 47 missing persons in the area. He is summoned by the oil tycoon Fred Schist to repress a strike led by the schoolteacher Teri Richards in his company.
He also learns that Schist claims that he bought the native sacred land Dark Waters from the Indian Ted Sallis that vanished with the money. Further, a man called Rene Laroque is sabotaging the facility. Kyle gets closer to Teri while he looks for Laroque, and soon he realizes that something in the swamp seems to be protecting Dark Waters.