The book is a series of ten stories, all featuring visits by children to the fairground. William the fairground car is the main character of the merry-go-round, and he has seven other named carriage characters as his friends. The title character and his friends talk to one another in a way that no one else can hear. The stories are told from the perspective of William the car and his friends, and their enjoyment at making so many children so happy. The target age is children 2 to 8 years.