In 1871, professional gambler John Devlin (John Wayne) elopes with Sandra "Sandy" Poli (Vera Ralston), daughter of Marko Poli (Hugo Haas), an immigrant who has risen to railroad tycoon. Sandy, knowing that the railroad is to be extended into Dakota, plans to use their $20,000 nest egg to buy land options to sell to the railroad at a profit. On the stage trip to Ft. Abercrombie, their fellow passengers are Jim Bender (Ward Bond) and Bigtree Collins (Mike Mazurki), who practically own the town of Fargo and Devlin is aware that they are prepared to protect the little empire...trying to drive out the farmers by burning their property, destroying their wheat, and blaming the devastation on the Indians. Continuing their journey north on the river aboard the "River Bird', Sandy and John meet Captain Bounce (Walter Brennan), an irascible old seafarer. Two of Bendender's henchmen, Slagin (Grant Withers) and Carp (Paul Fix), board the boat and relieve John of his $20,000 at gunpoint. Captain Bounce, chasing the robber's dinghy, wrecks his boat on a sandbar. At Fargo, the land wars begin and John teams with the wheat farmers against the Bender gang. Several attempts are made on his life and Collins tries to frame him for murder.