Pete Marshall is sent as a replacement to the mountain district town of Plainville when a public opinion surveyor who went there goes missing. Visiting the hillbilly family of Mamie Fleagle, Pete begins to suspect that she and her two sons have murdered the surveyor. Pete then believes that Mamie is slowly poisoning wealthy Grandma Fleagle, who has put a vital clue to her fortune in a nonsensical embroidered sampler.