A priest on a covert mission visits a little community one day. He is an Inquisition agent assigned to examine the actions of a local miller. The miller and his son are descendants of an ancient family whose ancestral home was destroyed by fire a century ago and then rebuilt from scratch. A great deal of the miller's expertise about the soil, water, and structural integrity of a structure was passed down via generations of his family. It has come to the attention of the Inquisition that he has a reputation for locating water and forecasting when structures would collapse; he must be in collaboration with Satan.