In this comic movie, Dennis Mitchell (actor Mason Gamble) tries in every way to befriend George Wilson (acted by Walter Matthau), the next-door neighbor. Dennis Mitchell causes Mr. Wilson much displeasure for most of the movie, including the time when Dennis' parents go on vacation and were unable to find a babysitter for their son. Dennis' time staying with the Wilsons (next door) during the parents' time away was not at all appealing to Mr. Wilson and Dennis' behavior once ruined Mr. Wilson's garden party. Throughout the time, a robber from another town was in the neighborhood and pickpockets valuables of the community, as well as harasses the toddlers which were Dennis' age. (The bandit also steals from Mr. Wilson during the time Mr. Wilson hosted a garden party in his garden.)

The wrath of Mr. Wilson to Dennis Mitchell about his constant embarrassing behavior, including spoiling the garden party, caused much emotional hardship for Dennis Mitchell and the child disappeared from the neighborhood. Days later, after spending time with the "robber in town" and living under the bridge where the train tracks were, Dennis Mitchell arrives back and brings Mr. Wilson's stolen gold back. Mr. Wilson realizes how harsh he was on Dennis, a five-year old, and befriends him.