Rogers has borrowed an old toy: a track on which marbles roll downhill. He shows that neither a large ball nor a cube (which he calls a square marble) can ride the track downhill (mindful of the 3-D cartoon Imaginit, which, at the time, was airing on several PBS stations between shows). Rogers plays a videotape of a "ball machine" that his friend George Rhoads designed and built. After screening the video, Rogers goes to the studio where Rhoads works. They plug in a different ball machine, one which strikes bells, chimes and gongs. It sounds musical to Rogers, but when it's turned off…Bob McGuire stops by. He shows Rogers other ball machines. George returns with a schematic of a ball machine with a cat's face and a skeletal chicken.
In the NOM, Lady Aberlin shows a mechanical toy, which delights Prince Tuesday. The Purple Jet returns King Friday XIII, who parachutes his way to the Castle garden. He says he saw the HulaMouse at the Museum-Go-Round and implores Lady Aberlin to return HulaMouse immediately. Lady Elaine is floating a ball a few feet from where HulaMouse is standing. Lady Aberlin shows her toy to them.
Back at the Castle, an angry Friday confronts HulaMouse. Claiming that Lady Elaine always intrudes on his business, King Friday insists the HulaMouse lives in the Castle. So stern is the King that he knocks over Lady Aberlin's toy, breaking it. None of that will shake Lady Elaine from working on her surprise. Prince Tuesday offers to help Lady Aberlin console King Friday XIII.
Back at the television house, Rogers says it can be scary when grown-ups get angry. Mr. McFeely invites Rogers to a catch game outside.
Songs: Won't You Be My Neighbor?, What Do You Do With The Mad That You Feel?, Good Feeling.