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. After Angel Face falls foul of one of Dennis's pranks on Sports Day, she gets her revenge by suggesting Dennis is 'leg cuffed' to Walter for the three legged race to keep him out of trouble. When, lo and behold, she 'loses' the key, she issues an impossible challenge to the menace and his reluctant wingman as payment for its safe return. After some embarrassing trials and tribulations, Dennis and Walter must overcome their differences and work together to outsmart her... temporarily at least.