Outlaws Spider O'Day and Sharkey Nye flee a sheriff's posse into Death Valley, California, but soon grow mistrustful of each other. They stumble upon Jack Belcher's little cabin and mine, watched over by Rex, a wild horse whose special mission is to protect the prospector's foster daughter, Toby. They plot to jump Jack's claim, but Spider has a change of heart when he falls in love with Toby. The enraged Sharkey suggests a game of checkers to settle the dispute. When Spider wins, Sharkey shoots him, then plans to do away with Jack and attack Toby, but Rex comes to the rescue and kills the villain. Spider recovers and is happily united with Toby.