The main part of this book is that the mystery gang get engaged in a circus.
They get to do crazy things and the one that gets the most wicked job is Velma who gets to be fired in a canon.
One of the main things that also happen in this that they hear about a werewolf stealing jewels. The mystery gang gets to know the artists the animal trainer says words in Spanish to some baboons. Fred gets engaged as trapeze artist the other trapeze artist called Oliverio he is menacing.
Daphne is engaged as a clown on motocycle to do some tricks. There is this clown called Schmatko who is never very happy and there is also this clown that does not talk, he honks. In the book Shaggy does his thing with Scooby.
After that they really love it but it's Shaggy that gets all the love from the spectators and Scooby is angry. The strong man that holds Velma once in the book is one of the werewolves in the book; the animal trainer is too.
The bit that I most enjoyed is when Shaggy throws some tranquilizer darts on the strong man's nose. The moment in the book that was the funniest is when they captured the two when they tried to get him into the car.