 Young Tom Fortnam is thrilled when he receives his guaranteed to grow mushroom seeds by special delivery mail. His father Bill is then approached by a friend, Roger, who thinks people are disappearing. Bill isn t quite sure what to make of it all until Roger s wife calls him to say that Roger has vanished, as has all of his clothes. When he visits Roger s house, he sees that Roger s son, who is the same age as Tom, is also busy growing mushrooms in the basement. Convinced there is a connection, Bill confronts his son - with fantastic results.