Frankenstein's unscrupulous colleague, Dr. Bohmer, plans to transplant Ygor's brain so he can rule the world using the monster's body, but the plan goes sour when he turns malevolent and goes on a rampage.
Molly Taylor owns the town of Stillwell but is unaware the taxes are due as Gomer has stolen her notice. Bob Martin arrives at the same time as Molly and eventually realizes Gomer is up to something. When Gomer's henchman slips and reveals there is a letter, Bob finds it and heads for the tax collector with Gomer's men in pursuit.
Bradley and sidekick Sharpe are sent west to investigate the murders of pony express riders who are being killed to prevent the Spanish Land Grant papers going to Washington for registration.
