The adventures of the rebellious schoolboy Dennis the Menace and his dog Gnasher
Whilst studying the school rule book in order to break them more effectively, Dennis discovers that the class prefect is allowed to bring a pet to school. There's only one problem: he can't abide by the rules long enough to be elected, so the menaces bend the rules instead and rustle up another candidate - Paul the Potato, naturally! Will they beat rival candidate Walter so that Pie-Face and Dennis can both bring their pals to the playground? Time for the menaces to get their election game faces on.
A disastrous P.E. lesson ends with Mr. De Testa trying to teach the culprits a lesson in teamwork - Dennis, Walter and Angel Face are now forced together to face rival school Greytown Prep in the annual Triathlon Competition. The team are fighting right from the start, but after a run in with the opposition during a training session, they decide to put their differences aside and unite for the win.