The book follows a typical day for Fungus the Bogeyman, starting when he wakes up and ending just before he falls asleep. As his day progresses, he undergoes a mild existential crisis, pondering what his seemingly pointless job of scaring surface people is really for. He is a member of the Bogey society, which is very similar to British society, but Bogeymen enjoy things which humans (called Drycleaners because of their contrasting environmental preferences) would not be comfortable around; for example darkness, damp, cold and over-ripe food. The book depicts the mundane details of Bogey life in loving detail, with definitions of Bogey slang and numerous annotations concerning the myths, pets, hobbies, literature, clothing and food of the Bogeys. Much of the humour derives from word play. For example, Bogeymen are shown to enjoy eating and sharing flies in a similar way to human cigarettes; one brand of fly is the "strong French Gallwasp", a pun on the cigarette Gauloises.