In 1896, Jeff Webster (James Stewart) hears of the Klondike gold rush and he and friend Ben Tatum (Walter Brennan) decide to drive a herd of cattle to Dawson City. On the way, he annoys self-appointed Skagway judge Gannon (John McIntire) by interrupting a hanging, so the "lawman" confiscates his herd. Jeff and Ben steal the animals back and take off with Gannon and his men in hot pursuit. After crossing the border into Canada, Jeff uses a few well-placed warning shots to persuade Gannon's gang to give up the chase, but the judge promises a hot reception when Jeff returns.
When Jeff gets to Dawson, he finds widespread (though relatively peaceful) lawlessness, and ignores it as none of his business. He auctions off his herd to new arrival Ronda Castle (Ruth Roman), a tramp and one of Gannon's business associates, when she outbids Hominy (Connie Gilchrist), Grits (Kathleen Freeman) and Molasses (Connie Van), co-owners of the local hash house. Both Ronda and French-Canadian gamine Renee Vallon (Corinne Calvet) are strongly attracted to Jeff.
Ronda sets up a saloon in partnership with Gannon and begins cheating the miners out of their claims. Gannon and his gunmen show up to grab their share (and then some), making Dawson much more dangerous. Jeff stays out of it, instead planning to sneak out by river while Gannon is otherwise occupied. However, Gannon is tipped off when Ben buys extra coffee for the long trip; his men kill Ben and wound Jeff, finally forcing him to take sides.
Jeff calls Gannon out to settle the dispute man to man, but the villain arranges an ambush. Ronda rushes out to warn Jeff and is fatally shot in the back. Jeff kills Gannon in the ensuing gunfight and the rest of his gang surrender to the fed-up longtime residents.
What city to Jeff and his friend Ben decide to drive a herd of cattle to?
Dawson City