On Mr. Wilson's birthday, Dennis's attempt to give him a collection of pets—including frogs, snakes, and even a baby alligator—leads to George accidentally riding a wagon down the stairs and getting a cake in the face.
Dennis’s maternal grandfather, Mr. Johnson (George Kennedy), moves in with the Mitchells, causing George to feel old and jealous of his more active counterpart. Dennis the Menace Strikes Again!
The story picks up with young Dennis Mitchell (Justin Cooper) continuing to be a "menace" to his grumpy next-door neighbor, George Wilson (Don Rickles). On Mr. Wilson's birthday