When his parents must go out of town on business, Dennis stays with Mr. and Mrs. Wilson. He is driving Mr. Wilson crazy, but he is just trying to be helpful, even to the thief who has arrived in town.
After a failed attempt to find the perfect birthday present for Mr Wilson, the mischievous little terror, Dennis, tries to save him from a pair of swindlers and their bogus youth remedies. Will he manage to keep their friendship strong?
To make sure that his beloved neighbour, Mr Wilson, has the perfect Christmas, the neighbourhood's lively six-year-old boy, Dennis Mitchell, makes a long list of things one needs to make it work. However, is Mr Wilson willing to change?