Deputized by U.S. Marshal George Higgins (George "Gabby" Hayes), singing cowboy John Weston (John Wayne) infiltrates the Dalton Valley Rodeo, a crooked outfit run by Spike Barton (Edward Peil). The gang uses a snake venom-tipped needle stuck in the saddle to ensure that no outsiders walk away with any of its hefty cash prizes, and also operates a profitable sideline as stagecoach thieves.