a photo journalist on vacation arrives at a small town in mid america to relax and do a little fishing . first and he find that all the fish have die . next he find the resident all paranoid and secretive and especially the owner of the local lodge . when he accidentally trespass on lodge property and he be attack by guard dog and and threaten by armed guard . none of the local townsfolk will talk to him except the doctor sister ( read love interest ) and the crusty old storekeeper . little by little he come to realize that the entire town be on a mission to develop germ and bacteria weapon which they intend to use to cripple america . i know the plot be preposterous . but you ain not hear nothing yet . in the original story and all the bad guy be nazi and they even have adolf hitler hide away at the lodge and but this movie be release in 1951 at the height of the mccarthy hearing and the commie scare . so all the bad guy become communist . only in the movie .