After buying up property around a Montana frontier town, land baron Rep Marlowe (Wendell Corey) tries to force out the homesteaders by damming the river, but Marshal Chaddock (Barry Sullivan) fights Marlowe's tactics despite little support from the cowed townsfolk. While Chaddock is on the mend from a snake bite, Marlowe and his henchman (John Russell) hatch a new plan to chase off the settlers -- by gunning down the lawman.