In it, Horace the Elephant holds a party for his eleventh birthday, to which he invites his ten best friends (various animals) to play eleven games and share in a feast that he has prepared.

He travelled to Kenya and Tanzania in 1987 observing animals in game parks and collecting ideas for the book.

[2] Written in rhyme, the book includes large and lavish full-page illustrations of Horace's opulent house and the events of the party, packed with hidden details.

The author invites the reader to deduce the identity of the thief by examining the illustrations and making deductions and observations.

The biggest and most noticeable clue lies in a paragraph of ciphertext at the end of the book, which is to be decrypted, once the reader has discovered the identity of the thief, by means of a Caesar cipher mapping A to the first letter of the guilty animal's name.