Mr Benn decides to find out what it is like to make people laugh, so he visits the costume shop to try on a clown outfit. But when he steps through the changing room door, instead of a circus ring, he finds himself standing in a field by a car. Mr Benn drives off down the road and soon meets a travelling circus, whose troupe asks him to join them; they all set off together - only to come to a halt when they reach a raging river. Seeing that the bridge has fallen down, each of the acts tries a different way of crossing, but all attempts fail. Mr Benn makes a suggestion: if they work together, they should be able to succeed…