A scientist and inventor named Wayne Szalinski lives in a house in suburban Fresno, California, attempting to create a ray gun capable of shrinking objects, but cannot get it to work properly. His marriage to his wife, Diane, is strained, because she has to be the breadwinner, which worries their two children, teenage daughter Amy and preteen son Nick, who has inherited Wayne's inventive ingenuity and intelligence. One morning, their next door neighbors, Mae and Russ Thompson, are getting ready for a fishing trip, but their older son, Russ Jr. is less than enthusiastic, as his and his father's interests often clash. Russ Sr is also upset that his son was cut from the team. However, their younger son, Ron is excited.