The film is about two brothers, Humkin and Mopekey, who live on a boat; the boat sits on land and is isolated in the middle of a field in some unspecified part of America. The two brothers live a solitary existence; they are clothed only in underwear, and have no communication with the outside world, with the exception of a few signals received through the ship's radio. Their sustenance takes the form of milk which is delivered by an equally mysterious milkman and a cereal consisting of frosted sugar balls; the origin of the food is not made clear.