Con artist Latigo Smith is on board a train travelling across frontier-era Colorado, with his would-be fiancée, a rich and powerful woman named Goldie. Looking for a way to escape this situation, he manages to slip off the train at a jerkwater stop, and finds himself in Purgatory, a small town wherein two rival companies of miners, led by Taylor Barton and Colonel Ames, are in a frantic round-the-clock race to find "the motherlode" of gold buried somewhere under the town.
After consulting the town doctor about getting an embarrassing Goldie-related tattoo removed, Latigo succumbs to a gambling compulsion and loses all his money at roulette. After hearing a rumor that an infamous gunslinger named "Swiftie" Morgan is in town, Latigo concocts a scam, using the amiable ne'er-do-well Jug May to impersonate the man. In the process of this, the new arrival attracts the attention of Patience "The Sidewinder" Barton, the hot-tempered daughter of Taylor, who wants nothing more than to escape the town and become a woman of refinement in New York City. When Latigo and the fake Swiftie side with the Bartons, Ames sends a telegram to the real gunslinger, informing him of the impostor.
Swiftie soon arrives in town, and confronts Latigo, who has replaced Jug for the climatic gunfight. The show-down ends with Swiftie shooting himself when he is startled by one of the massive mining blasts that regularly rock the town. Latigo accidentally finds the motherlode for the Bartons by setting off a load of dynamite with which he was attempting to bluff the gunfighter. The blast also cures his tattoo problem.
Latigo's gambling compulsion finally pays off when, financially backed by the Bartons, he wins big at roulette. Now almost as rich as Patience, he marries her, she gets to send her numerous daughters to school in New York, and Jug goes on to "star in spaghetti westerns."