It's 1883, and the silver boom is well underway in Colorado. Penelope heads to Denver to use her witchcraft to steal a necklace from Diamond Betty, a beautiful woman with a questionable past who recently married a wealthy silver magnate almost twice her age. The diamond pendant contains a demon, and Penelope plans to put the necklace in a place so safe that no one would ever be able to harness the creature's magical powers. But things don't always work out as planned, especially when magic—and demons—are involved.