Dennis and his faithful hound Gnasher are out to make every day as much fun as possible, but their adventures often lead them into trouble. Walter shows off some new tricks on his fancy skateboard, prompting Dennis to make a jibe that even his Gran could do tricks like that with such a high-tech board... the bet is on! But Walter secretly sabotages the trick, causing Gran to hang up her menacing shoes as a matter of public safety. It's up to Dennis, Gnasher and Angel Face to expose the truth and get Gran back to her wily self, and to put Walter back in his place!