Scotch John MacGregor's burning ambition is to become as famous an outlaw as his forebear, Rob Roy. And he is well on the way to achieving this aim. He and his gang rampage across the State of Colorado, robbing banks and holding up stagecoaches. However, when Pinkerton agent Dave Lansom meets up with the renowned Kentuckian gunfighter Jack Stone, they combine to track down the outlaws. Soon, Scotch John discovers that he's up against a formidable team.