Everybody's favourite human tornado, Dennis Mitchell, does not walk - he either runs or rides his bike. His boundless energy, enthusiasm and, most of all, curiosity, are sometimes more than most people can take, but his heart is certainly in the right place. It's his next door neighbour good ol' Mr Wilson who usually finds himself the unwitting object of Dennis' pranks but, luckily, his wife is always on hand to smooth things over between the unlikely pals.