J.P. Judson, a haggard old man, arrives at the farm. He tells Aunt Bea that he's a Dowser and can find water with a divining rod. She offers him a room in the barn until Sam comes home the next day. Sam comes home and tells Aunt Bea that he hired a company and their geologist will be there in the morning. She talks Sam into letting Judson stay to watch the geologist. Mr. Harris arrives and finds a spot were he'd like to start drilling. Judson checks the spot out and says they won't get any water there. Harris drills anyway, but comes up dry. Later, Judson claims to have found a spot and only wants $50 to show Sam where it's at. Sam says he's going to stick with Mr. Harris. The next day Sam tries using a diving rod and Aunt Bea sees him. But he's still going with Mr. Harris. Harris drills another hole and comes up dry again. Harris bets Judson that he can't find water and Judson tells Harris to keep drilling where they are. Harris drills another 20 feet and they hit water.